Thanks for this Ramshackles! It wasn't until you spelled it out there that I realised how flippin lazy I am when it comes to recording! And when you consider how much work I put into writing the songs, don't you think they deserve a bit of graft when it comes to capturing them. I always told myself performance was everything.
Two questions: does the mic placement advice still hold if you're using a dynamic mic? The reason I tend to avoid my condenser is because it's a bit thin, and my rooms never sound good. Maybe I'm not anywhere near this sweet spot you speak of?
And why cut volume instead of boost? What about fader riding? I NEED TO KNOW MORE PLS 
Lol...I'll try to answer
Dynamic mic placement - essentially, yes, placement makes a difference. Although dynamic mics are heavily directional, the reflections going into the front of the mic can still change depending on where you position it. Having said that, you'll probably find it way less noticeable than on a condenser. Placement on an instrument still matters as well, since the tone of the instrument is different in different places (e.g. listen to a guitar at the neck, the sound hole and the bridge).
All rooms have a sweet spot, but it is 'sweet' relative the rest of the room... a bad room is a bad room
Volume cuts instead of boosts. Basically this is about maximising your signal to noise ratio.
So, lets say you have recorded with an optimal gain structure - that is the gain on all the elements in your signal chain is the maximum it can be without clipping. So what we have recorded has the best S/N it can.
If you boost, you are going to be boosting noise as well. Lets say you have 5 tracks and 2 or 3 you want louder. You have just boosted noise on those tracks! If you were to cut the other 2/3 tracks instead, your overall noise would be lower for the same relative volumes. Another problem with boosting is that you run the risk of clipping or at least severely reducing your headroom. You'll need that headroom in the mastering stage!
Final reason (and arguably the most important) is that there are so many gain/volume controls in a signal path that it is easy to end up in a situation where you a boosting somewhere, only to cut it later. Once you have done that, the net result is null, but a few dB of precious headroom have been irretrievably nuked
If you aim to only ever cut, you are unlikely to encounter the problem.
The same rules apply to EQ, although there are loads of articles detailing other reasons why cutting is better than boosting.
Of course, some laws are made to be broken....
