Ideally, of course yes.
You are altering a mix by adding elements afterwards, so I would think you would want to hear what you are doing as best you can, with a calibrated sound system.
And you mean 5.0 stems, not 5 stems
When a film is mixed, it is printed to multiple stems
one 5.1 stem for Dialog DX
one 5.1 stem for Music
one 5.1 stem for SFX/AMB/Foley
These stems are then combined in a mastering pass (print mater) to a single 5.1 mix.
Are you getting THREE x 5.0 (in your case) stems?
or one 5.0 final mix combined stem?
What happens after you finish your work?
Are the stem/s and your LFE additions taken to a proper film dub stage & print mastered?
If I was you I would want to know the answer to this question.
If the stem/s and your LFE additions ARE taken to a proper film dub stage & print mastered, then there is a final check of your work & the final soundtrack.
If the stem/s and your LFE additions ARE NOIT taken to a proper film dub stage & print mastered, then there is a possibility that you are doing the final pass, in which case I personally would not touch the project.
ALSO: I will add, I am not a film rerecording mixer. I have been sound designer & supervised on many (40+) films but the work you are doing is that of a rerecording mixer, and I would suggest asking your question at that GearSpace Post forum, as there are many film rerecording mixers there & they would be far better to advise you than I am. I don't see re-recording mixers on VI Forum.
Post Production Forum - Audio Post Production for Television, Film, Video and Radio.
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