The principle of doing things in the last responsible moment on face value looks a dangerous proposition, especially for those who believe in getting things done well in advance. I had to fairly do some research to understand what this principle actually says and if it at all holds any water.

Kas Thomas from Big Think says that the key intuition is that crucial decisions are best made when as much information as possible has been taken into account.

This is a good tactic when the following criteria are met:

1. Not all requirements for success are known in advance
2. The decision has huge downstream consequences
3. The decision is essentially irreversible

If one or more of the conditions is not met, the tactic of deferring commitment might not gain you anything (and could actually be costly, if it holds up development).
The principle of last responsible moment accepts the fact that you cant know everything in advance. Hence, reject the arrogant notion that with proper advance planning, you’ll have a project that goes smoothly and results in a usable solution.

Everyday Kanban in its post says that Doing things before they need to be done is a type of waste and a main tenet of Lean is to reduce waste. If you are doing things that don’t yet need to be done then you are, presumably, NOT doing things that DO need to be done. Call it misguided prioritization and/or opportunity cost. You are costing yourself, your team, your company, the opportunity to produce something that is more beneficial to them in that moment than delivering something that is not yet needed.

As Coding Horror mentions it as a parting shot:

“Be prepared. But for tomorrow, not next year. Deciding too late is dangerous, but deciding too early in the rapidly changing world of software development is arguably evenmore dangerous. Let the principle of Last Responsible Moment be your guide.”