Set reverb distance with the return fader
A part placed at the right distance in the mix, with the gaps between phrases still clean.
The problem
A reverb that sounds lovely in solo can wash over the next phrase in the mix. Long tails are easy to fall for on their own, and they pile up when the whole arrangement is playing.
What to do
Set the dry part at its level in the mix first. Then bring the reverb return up from silence with everything playing, and stop when the part sits at the distance you want. How far away something sounds comes mostly from that balance of dry and wet.
Only then touch the reverb itself, one control at a time. Decay sets how long the space rings. Pre-delay sets when it starts, which keeps the front of a word clear of the space. Knee Verb's Pre-delay goes up to 250 ms. On a vocal send, start it low and raise it until the start of each word separates. Then set Decay so the tail clears before the next line.
Use a long loop for this, a whole phrase and the gap after it. A loop of one bar hides how the tails pile up.
When to stop
If you notice the reverb before the part, it's too loud. Pull the return down a decibel at a time until you'd miss it if it went. Listen where instruments stop and where the arrangement gets dense, and automate the return if a section needs a different space. A short, quiet space often places a part better than a long, loud one. If the tail still blurs the next phrase, shorten Decay before you pull the level down any further.
The test
Mute the return, then unmute it, in the busiest section. The part should move back into the room without the words or the attack getting softer. Then check mono, where a wide tail can get louder or thinner, and keep the setting that works across the whole section.
Rory