A lot of game development does not work like that. Bugs are often their own unique tasks with many unknowns which makes time estimates vague. Many bugs are also not yet discovered, so how do you estimate time for something you don't know exists? Right now we know about x amount of bugs we want to fix, but each day testers may find zero or 5 more that are must fixes, which then takes of x amount of time each. One could be 10 minutes, another 3 days.
Except when we say 80% of bugs fixed and then the next day say 76% of bugs fixed as new ones are found. They will LOVE IT!