Your instruments should be available for immediate use at all times.

Bwahahahaha! You mean the cover might slow down use of the compass? Is your
cover attached with a complex magnetic lock? Is it welded down, requiring a
torch to access the compass? Is the cover covered with some type of Arrow Frog
poison requiring special gloves to remove?
You're right, Donal! I can't possibly risk the 1/4 second to remove that
cover!!!

Bwahahahahahaha!

RB