Hey thanks for posting!
Yeah, using the conventional Effect and Aux loops is okay during a mix when you're sending everything to the Stereo Suss and hence to whatever you have that passes for a mixdown machine. But if you're doing a bounce and you want to put an effect on an instrument you can't really use the Effect Returns or the Stereo Ins to bring the signal into the mix as they're hard wired to the Stereo Buss. Which means using either spare Channel Inputs or Buss Ins.
An example.
I recently recorded a song that had the following arrangement:
Track 1: Lead Vocal
Track 2: Lead Guitar
Track 3: Second Lead Vocal and Guitar Solo
Track 4: Bass Guitar
Track 5: Rhythm Guitar & Backing Vocal #1
Track 6: Rhythm Guitar & Backing Vocal #2
Track 7: Drums & Percussion
Track 8: Drums & Percussion
The first step was to lay down the Drums (from an old
Yamaha RX21) and the percussion (four tracks: a tambourine, claviers, shaker and some wooden thing). Thus
Track 1: RX21 Left Output
Track 2: RX21 Right Output
Track 3: Tambourine
Track 4: Claviers
Track 5: Shaker
Track 6: Wooden thing
Track 7: Guide Vox
Once that was done I had to bounce the recorded instruments from Tracks 1 - 6 to Tracks 7 & 8 to make way for the other parts. One of the things I decided to do during this bounce was to add reverb to the drums: primarily because the RX21 has no built-in FX and if I'd added reverb to the drums along with everything else during the final mix there'd be no way I could control the amount of verb on the kick. By using the line inputs on Channels 7 & 8 as Effect returns I could get some semblance of control over the reverb in the low end by setting the equalisers in these two channels to cut drastically below 200 hz. What I also wanted to do, however, is use my other FX unit to achieve a ping-pong echo on the claviers (to give a sense of movement). Since I'd already used the only two spare channel inputs, I thought I'd experiment by using the Buss Input of Track 7 for an Effect Return. And it worked quite nicely. Of course I could have used the Insert Return on that channel instead but I was using that for a compressor return (I prefer to compress each instrument conservatively during tracking and then add a smidgen to the whole lot during a bounce) So that option was closed. Hope that explains my thinking behind the question.