SiliciumHex FieldKit

Design to Cost · Value

Useless Function Hunt

Challenge every function: who needs it, what breaks without it, what does it cost? Kill the orphans.

  • Time30 min
  • FormatTeam
  • StageValue

Useless Function Hunt: what it is and why it works

The useless function hunt is a short, focused review that challenges every function of a product with three questions: who needs it, what breaks without it, and what does it cost? Starting from the function list produced by functional analysis, the team links each function to the requirement it serves. Functions that serve no requirement are flagged as deletion candidates, and so are functions serving a requirement no customer has mentioned for a long time, such as the last two years. The potential savings are listed and validated with the product owner before anything is removed.

Products accumulate functions over time. A customer asks for a feature, an engineer adds a safeguard after a one-time problem, a specification is copied from an older project, and years later nobody remembers why. These orphan functions continue to cost money in parts, assembly, testing and documentation. Deleting a function that no one needs is often the cleanest cost reduction available, because it removes cost without degrading anything the customer values. The hunt draws on the function cost audit practice of value analysis, uses the FAST diagram to see how functions relate, and supports complexity cost reduction by removing variety and parts at the source. Safety and regulatory functions are never deleted on cost grounds; they can only be delivered more efficiently.

What you need

  • The function list from functional analysis, ideally with a FAST diagram
  • The requirement or specification behind each function, where known
  • Cost per function or per part
  • Customer, sales and service feedback from roughly the last two years
  • Applicable safety, regulatory and contractual requirements

What you get

  • A list of functions with no identified requirement
  • A list of functions serving requirements no customer has recently mentioned
  • Estimated savings from deleting or converting each function to an option
  • Decisions validated by the product owner, with safety and compliance checks recorded

When to use it

When the product carries features whose original requester has left.

How to do it, step by step

  1. Take the function list from the functional analysis.
  2. For each function, ask: which user requirement does it serve, and what does it cost?
  3. Flag functions serving no requirement — candidates for deletion.
  4. Flag functions serving a requirement no customer named in the last two years.
  5. List the deletion savings and validate with the product owner.

Worked example: Control panels for water pumping stations

Illustrative scenario — figures are realistic but not from a real company.

A panel builder supplied about 150 control panels a year for municipal water and wastewater pumping stations. The standard panel had grown over a decade of customer requests, and the product owner suspected some features no longer served anyone.

  1. The team started from the panel's function list and, for each function, noted the requirement it served and its cost per panel.
  2. Three functions had no current requirement: a thermal alarm printer added for one utility eight years earlier, local pump hour meters duplicated by the plant SCADA historian, and an anti-condensation heater fitted to every panel, including those installed in climate-controlled rooms.
  3. Manual pump control and local emergency stop were confirmed as required for operability and safety and were excluded from the review.
  4. The team estimated savings per panel: about $620 for the printer, $95 for hour meters, and $180 for the heater on indoor panels.
  5. The product owner checked recent tender specifications and consulted three utility customers before approving the changes.

Result. The printer was removed from the standard design and offered on request; hour meters were dropped where SCADA was present; heaters became standard only for outdoor or unheated installations. Savings averaged roughly $700 per panel. The team noted that the hardest part was not finding the orphans but confirming that no customer still relied on them.

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Common pitfalls and how to avoid them

  • Deleting a function without checking contracts, specifications or regulations.Verify each candidate against current tenders, standards and customer contracts before deleting it.
  • Treating safety functions as potential orphans because no customer asked for them.Exclude safety and compliance functions from deletion; challenge only how efficiently they are delivered.
  • Relying on memory to decide whether customers still need a function.Check sales, service and tender records and ask a few customers directly.
  • Removing a function outright when some customers still value it.Convert it into a priced option instead of deleting it from the range.

Frequently asked questions

How do you identify unnecessary features in a product?

List the product's functions and link each one to the requirement it serves. Features with no requirement, or whose requirement no customer has mentioned for a long time, are candidates for removal. Check sales, service and tender records, and ask a few customers directly. A FAST diagram can also reveal functions that serve no higher-level need.

What should you do with a function only one customer uses?

If the customer still values it, consider making it a priced option or a customer-specific variant, so its cost is carried by the customer who needs it. If the customer no longer uses it, confirm this and remove it. Avoid keeping it in the standard design, where all customers pay for it.

Can removing features hurt sales?

It can, if the feature matters to customers or appears in specifications. That is why deletion candidates must be validated against customer feedback, tender specifications and contracts before removal. When a feature is truly unused, removing it lowers cost without affecting sales, and the savings can support pricing or investment in features customers value.

Origin

Function cost audit — value analysis practice (L. D. Miles tradition).

Used in these playbooks

Complexity pruning quarter 1 quarter

One quarter to cut what variety costs: measure complexity, standardize parts, modularize the platform and delete the functions nobody misses.

  1. Complexity Cost
  2. Standardization Push
  3. Modular Architecture
  4. Useless Function Hunt

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