My go-to reference for this is Evidence-Based scheduling. In a nutshell, the methodology is to NOT change how you estimate—why fight the behavior you're so accu

My go-to reference for this is Evidence-Based scheduling. In a nutshell, the methodology is to NOT change how you estimate—why fight the behavior you're so accustomed to—and instead measure how past estimates differed from actual delivery time. Over time, the model you train can become very accurate at estimating and—importantly—does not require you to do anything different than you normally would. Link [0] Now here's the other important thing! You must realize that there are multiple types of tasks and they require different kinds of estimates. You can use the Cynefin framework[1] to categorize problems into one of a few domains: For problems in the Simple domain ("known knowns") you can give an exact number on how long it will take, because the solution is known to you and there's absolutely no uncertainty. Problems in the Complicated domain ("known unknowns") have some up-front questions that can be answered, and you have the capacity to answer in the requisite time—these problems you give an estimate on, because you don't literally know how long it will take but you have an idea. Problems in the Complex domain ("unknown unknowns") have a high amount of uncertainty. You must at least start work on them in order to fully understand the problem and the realm of possible solutions. Use Agile here and let the client know that there's multiple steps involved and it's very hard to give a good estimate. Give the client the estimate for the first step and let them know you'll be able to get back to them with more information. If they _require_ an overarching estimate, think really big so when those "unknown unknowns" show up they can't bite you in the ass. 0: https://www.joelonsoftware.com/2007/10/26/evidence-based-scheduling/ https://www.joelonsoftware.com/2007/10/26/evidence-based-sch... 1: https://en.m.wikipedia.org/wiki/Cynefin_framework https://en.m.wikipedia.org/wiki/Cynefin_framework