For example if I'm going for a wide & tight pop-rock overheads sound with a spaced pair, then I'm having them to be of equal distance to the snare because that will be the most important element. Drums are complex of course and as you fix one thing you will get issues in other things, so you must determine what matters the most and go with it. Then in post I will also experiment with phase alignment tools to see how that works out. But there is no right or wrong here, as what ultimately matters is whether it works and sounds good for the track. The "phase-aligned" drum sound is a special sound that can work beautifully to add some serious tightness and punch, but other times it is best to stick to what you had going in. The key is to listen of course and in context with the track.
For guitar cabs - "phasing" is quite often a big part of the sound itself so it just becomes a matter of moving things around until it sounds good. Other times the "nulling" trick can come in handy and it's quite a nice trick to have - you flip the polarity of one of the mics as you move it around some loud amp hiss, until it almost nulls with the other mic, and then you flip it back. This will give a really good phase relationship that will be most noticeable in the low end - perfect for a big & beefy guitar sound.