Let's say you don't have the time to give it the complete understand-and-write-unit-test-suite approach though.
How are you verifying you fixed the bug otherwise? By changing some code, building the app, and running it to verify the bad behavior doesn't happen anymore? I don't really see how not writing a unit test (assuming the code is unit-testable in the first place) saves you any time. You are doing testing anyhow.
And if it was a critical bug, personally I'd want to feel as confident as possible that I fixed all permutations of it.
How are you verifying you fixed the bug otherwise? By changing some code, building the app, and running it to verify the bad behavior doesn't happen anymore? I don't really see how not writing a unit test (assuming the code is unit-testable in the first place) saves you any time. You are doing testing anyhow.
And if it was a critical bug, personally I'd want to feel as confident as possible that I fixed all permutations of it.