The location recordist did a good job
and the two sounds are balanced
nicely. I like it (sfx editor)
In my opinion, herein lies the root of the problem - particularly the last sentence.
M&Es are oddly enough a great example of instant karma - race through your edits and the M&E is likely going to take a lot of time to build. Take time and properly build your tracks strategically up front, the M&E is going to be a breeze. in a perfect world, we would all take our time up front. But we're not in that perfect world, and budget/time constraints sometimes result in needing to brute-forcing our way through an M&E.
That being said, as sound effects editors and foley artists/mixers/editors, we're obligated to do wall-to-wall coverage on everything. No matter how cool or full-bodied something may sound in production (and 9 times out of 10 the PFX is lacking in some way and at least needs to be sweetened), especially if there's an overlap, when I cut sound effects I always give the stage my own version of a full build (or if it's something Foley covers, they do full coverage) - that way it plays in the mix, and subsequently, it will match for the M&E (or if it was mixed against the cool PFX overlapping dialogue, it sounds incredibly close for a match in the M&E when the PFX blend goes away).
From a dialogue side, this is one of the main reasons I'm quite anal about cleaning out ticks, pops, etc, splitting out all free-and-clear PFX, and addressing all overlaps with clean alt takes or ADR if necessary - getting the dialogue track as clean as possible up front, so that you can more or less mute it for the M&E over 50% of the work is already done. Failing the ability to eradicate the overlap issue, I make sure sound effects and/or Foley coverage takes care of that section too, knowing we're going to have to blend any residual PFX with the cut FX version for a blend.
As Justin pointed out, there can be issues of legality with residual dialogue, and this is can be why QC houses are strict. And I actually know a colleague who had an M&E bounce one time in Germany for that EXACT reason - even though he couldn't figure out what English they were hearing. Either way, it had to be re-filled. Usually QC houses will never want any sort of breath, grunt, moan, or other non-linguistic vocalization present - and they expect every little single detail (down to the hand pats) to match - this part is exactly why I get my dialogue tracks as clean as possible. The less oddities there are sitting in the dialogue track, the less there is which has to be filled/re-built/remixed for a sync match. And by having full coverage on your FX and Foley, then you can find what you need by playing the faders.
And again Justin is correct, backfilling is a must - but hopefully by properly preparing the dialogue track, most of the work's already done for you (and even more so if the dialogue premix turned out really clean and the dailies were clean too)
It can be nice to provide an Optional track for Group ADR and related cut FX elements (e.g. dispatch radio edits, callouts edited to blend with the BG, speaker pages like Hospitals, etc). That way its not part of the M&E itself, but when the M&E gets remixed with the overdub, they have the option if they want it - especially for something like radios which play so low they're more of texture, but nonetheless, if it has English, it will need to be maintained separately otherwise it will likely bounce QC and be problematic down the road - the Optional track is great for this kind of thing.
Hope this helps! M&Es can be a very strict and disciplined process to learn, but it's a fantastic opportunity to learn how to think '2-steps-ahead' about organization and editorial to result in a smooth printmastering process.