I remember that discrepancy in methods back when I first started fiddling with it... however you have to consider WHY you might put it at the end of the signal chain of a PC strip. If you were using an external tube pre or compressor in a hardware situation you'd likely have that BEFORE the board, nest'ce pas? It could also be looked at from the angle of how a board with internal compression/EQ and the like handles an input. Like will the signal go through the EQ section BEFORE it starts humming around inside the board? Where exactly would sound the CE creates actually come from within a hardware board?
So you might want to look at the ProChannel itself a little differently. What modules would you consider to be something you'd use as an external pre-input effect, what would you consider to be an onboard effect (and where would it sit in the signal chain within the board) and finally what would you consider to be effects that are being fed by the output of the board.
Obviously it doesn't need to be overly complex but once I started looking at the CE in those terms I found I could manipulate it more logically and get better results. I personally use it in kind of non standard ways anyway. Like on some tracks I find it sounds really good but on others it kind of sucks the life out the sound or makes it seem lo-fi while other times there doesn't seem to be any difference at all. So instead of throwing it on all the channels at the start I'll get a rough mix together then try it out solo'd on each track and then in the mix. Sometimes I'll even mix and match. Then I'll do the finer mixing with the modules in place.
Also putting the CE at different points in the PC chain can have some very different results especially with compressors and tube modules in play. Actually screwing around with how it's placed in relation to the FX bin loaded up with some heavy duty distortion or other really noticeable effects gives a pretty good example of what happens when you drive the CE with the signal as opposed to just turning the CE drive knob.
I have even tried doubling up the CE on certain channels or buses which can be interesting. I guess that could be looked at like tracking with one type of board then mixing through another. Many many possibilities.
Other people however say they can't hear it doing anything... so maybe I'm just crazy. lol