A short thread discussing some approaches to “over the shoulder” mic techniques:
What is happening when you put a mic ‘over the shoulder’ is that the mic is hearing pretty much what the ear is hearing… except that the ear is able to distinguish between reflections as distinct events and a microphone does not have that capability.
… and some insight into phasing issues with overhead drum mics:
What will be immediately noticeable (in terms of phase issues) is the snare sound. If you are using a spaced pair (two mics seperated by a significant distance) one way to solve that is make sure both overheads are exactly the same distance from the center of the snare.
But make sure you understand what causes phase problems – it is what happens when the sound from a single source is picked up by two or more mics that are different distances from the source.