The trouble is it's hard to think of and through all the possible failure modes while in the air.
A few years back I did a very long trip. On the outward leg, Palo Alto to Denver, I flew high (FL200) and noticed that I had just a little bit less boost than I expected - the throttle was pushed in a little further. (On the TR182 the second half of the throttle movement is actually gradually closing the wastegate).
I didn't worry about it, I figured the rather complicated linkage must be out of adjustment. On the ground in Denver I took the cowling off, but the linkage is both complicated and well hidden and I couldn't see anything obviously wrong.
The journey home was in several stages. At each stage I was getting just a little less boost. Finally in Lancaster (fuel/lunch stop) I had a mechanic take a look at it. Ouch! It had nothing to do with the linkage. The locknut on the turbo impeller had come off and was gradually chewing up the aluminium impeller. By now there was very little left.
Had I known that, I would certainly not have been flying over the Rockies at 2000' AGL!