big studioa have an ssl or neve. the ssl is an inline console. which means that input and return are in the same module or strip. there will be 2 faders , one for each path and in the master section u can change which is which depending on your needs. as you can have a setting for mix and record or both.
the insert in the patch bay will reflect those settings. so you will have the mic into the console hwere u choose to use an outboard pre or the ssl pre. for the outboard pre you only patch in and out you fav pre.
then you choose if u want to record to tape the EQ and compressor or not.
and the gain to tape will be one of the faders in that channel strip.
then for tape return you can patch so it goes to another channel or the same. you can only use the EQ and compresor in one path but not both. this is usefull if u want to eq or compress the monitor path and send it to headfones cause your singer was told that if the kick drum was compress she could sing better or whatever.
usually u are able to change if the compressor comes before or after the EQ on each channel strip.
if u are only mixing you can use one fader for volume and the other as a send.
again , with patching.
the patch bay is one of the most important parts. not only because of routing but also it is the center or main ground. so compressors and other outboard gear will not have that 3 ground pin on the AC outlet but instead will be routed to the patch bay, this is becuase is if something goes wrong itll go to the poatch bay which is grounded to the ground or the easiest and fastest way to the ground instead of you.
of course u can risk it and not routed this way but usually big studios are set this way.