why/when would u put an effect insert in the i7 or i8 slots in the channel editor.
As the other two posters have suggested, pre-fader slots make the most sense with plug-ins that are dealing with dynamics…like limiters, expanders, gates, compressors, deessers…etc.
The reason is, in post fader mode, the channel fader affects the level of signal the plug-in’s threshold detection circuit sees, making it near impossible to set a specific/critical threshold setting if there is to be any kind of fader movement on that channel.
Example: A gate’s threshold would change as you raise and lower the fader in post mode but would not if you were in pre mode.
Another example: A compressor on the mix buss in post mode. What happens to the mix if you were to fade out? The dynamics would change as the mix drops below the threshold level of the compressor. In pre mode, this would not occur.
I agree with ebryants comment about making all the inserts pre-post switchable for more flexibilty. It is rather shortsighted to assume that you only need two pre fader insert effects slots per channel…particularly on output busses.