The funny thing is, that "last squirt" muscle is still there, it reacts and you can feel it, except it does nothing.
As mentioned, you just go until it stops and that's it.
Immediately post-surgery the important thing is that you can pee.
Initially it might be like your upstairs neighbors having an overflowing tub, it just leaks through the ceiling everywhere.
Eventually it will stabilize to a nice stream.