Avoiding memory-allocation deadlocks

yes and no

when a lock in introduced, there is a lot of analysis to try and make sure that there are no problems. It's not haphazard and ad-hoc

However, when you get a random bug report to analyze, you don't know if it is a locking error, what lock it could be, in what subsystem, let alone the changes since that lock went in place.

remember that in the last release cycle, there were just over 12,000 different changes from 14,000 individuals that added 591,000 lines of code while removing 250,000 lines

with the code this large, nobody can keep track of everything, and you can't put out a call to everyone to look at any one bug (let alone all of them).

The bisection approach lets you narrow down where the problem was introduced, so that you can get the correct people involved to troubleshoot it.

It's actually an incredibly efficient process, as much as it seems ad-hoc and haphazard at first glance.