If you haven't watched all of Dan Worrall's stuff, I highly recommend it: https://www.youtube.com/@DanWorrall. He also does tutorials for FabFilter's stuff, but in a general way such that it can apply to everything ("Introduction to..." series). Here's a few tips I've picked up on:
-Reduce the stereo width for your kick channel to mono or near-mono, and consider it for the bass (maybe don't go all the way to mono for bass)
-As far as I know, it's generally a good strategy to HPF each track up until it starts affecting the sound. The low frequencies stack and build, especially after reverb + effects, after combining multiple tracks, etc.
-On the master, cut all the sub-bass with a HPF @ 20 Hz - you won't hear it anyway. Consider setting it a bit higher depending on your mix - for music you don't always want the 'rumble' of low bass frequencies.
-Definitely try a HPF @ ~90Hz for just the side channel since our ears generally aren't sensitive to lower frequencies on the sides. Depending on the specific content of your mix, this may change your stereo image for 90Hz and below (due to phase differences in the filter's slopes and target Hz) - if it sounds worse, play with the slopes of the 20Hz HPF and the 90Hz HPF or use a linear phase EQ for this specific HPF.
-Try HPF'ing your input to your reverb so that lower frequencies aren't 'verbed (probably want a shallower slope for the filter here). Or at least ducking the wet low frequencies on a new note.
Why care about the phase so much - are your filters not clean (e.g. there's a resonant bump at the target frequency)? Your ears only pick up on the relative phase differences e.g. if you have different phases at a frequency on the left channel vs right channel or mid channel vs side channel (you can give some width to a mono track by using e.g. a 12dB/oct HPF on L channel but a 24 db/oct HPF on R channel at the same frequency). But you should be able to use steep filters on individual tracks without issue (as far as phase is concerned). Phase can be a problem if the stars align and a bunch of individual waveform peaks line up, but that would very likely only be an issue for that individual note and not overall.