QDM,
Learn the theory - that way you'll be able to handle any written exams, even if it takes you a minute to figure it out.
As for the practice, there are two times you'll need to understand compass errors - if your DI fails (simulated or real failure), or if you're flying an aircraft without a DI. In the former case, make all turns shallow enough that it makes very little difference. You won't need to worry about acceleration errors, because you can just continue flying in a straight line any time you accelerate. And if you're ever fortunate enough to fly a "real" aircraft with no DI, start off gently, and I'm sure it'll start to become instinctive before too long!
FFF
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