Client: "How much will it cost to build this whole software?"
Manager: "I have no idea, but I'm going to give you a number anyway so you trust me"
This is how it actually goes.
Traditional project estimates relies on predicting the future based on mere assumptions, often leading to inaccurate estimates and missed deadlines. They do get lucky sometimes, and finish on time, scope and budget, but that's just luck, basically gambling with your money, the house never loses, you do.
Giving you a full budget estimates is literally impossible, unless, we did the same exact thing before with the exact same variables. Reality says that never happens.
Instead, we provide you two weeks estimates, based on the sum of all the tasks data (using PERT), and since tasks are billable, the estimate comes with a monetary range, but not more than that, maybe a month only and only if we have enough data. What we can guarantee is a transparent view of our progress and costs. What we can also guarantee is a working software multiple times a day/week, you don't have to wait for your software to be delivered by the end of the year as a black box. No, you see it in real time, you see every little detail, and you can pause it at any moment, continue at any moment, take it off at any moment, it's still transferrable.
Rather than predicting how much can be done within an arbitrarily amount of time, based on nothing. We can forecast project progress more accurately by monitoring the rate in terms of measurable deliverables in real-time, and adjust priorities accordingly.