The carpenter rarely discovers a few days in that the screwdriver they have to use on this project only works every other week. Or that literally every measurem

The carpenter rarely discovers a few days in that the screwdriver they have to use on this project only works every other week. Or that literally every measurement on every component is off by 20% because "that's how it's done" with whatever garbage you stuck them with. Vendors and even open-source libraries are often liars or just missing what seems like it ought to be obvious functionality. Sometimes tools are just broken. I once was assigned a Java AWS Lambda project, which, great, supported, right, says so right on the website? Except half the CLI tool functionality just didn't work, at the time, for Java projects, and I mean the official tools. It was alpha-tier supported at best. Usable, sorta, kinda, but you're gonna lose some time un-fucking the situation, and the whole thing would be slower to develop than it needed to be. You'd not know that unless you went and did a focused search on their issue tracker(s), which isn't really reasonable to do for all the stuff you might use in a typical project (some of which you might not even know you need until you've started work). "Great, so now you know that for estimating next time, if you get assigned a task exactly like that one" well, no, not really, because that was like four years ago and the situation's probably totally different now (maybe better, maybe worse, who knows?) That's why I think giving 4-8 weeks of development time with some basic t-shirt sizing or pointing for tasks and just seeing how it's going is better, before estimating. I think if you can't afford that, before getting the estimate, you can't afford a half-decent estimate at all and just need to deal with the fact you're going to get a terrible estimate with an absolutely huge range ("six to eighteen months"). Which, fine to ask for that up front then refine it after some dev time! It just needs to be clear and expected that those early estimates are going to have some wild variance—but they can definitely tell you "is this more a 1-year project, or more a 5-year project?" which does have some real value.