I have to be cautious here. It is almost 20 years since I did my course. At the time I am pretty certain that all of the agencies had the rule, if in doubt bailout.
I don't teach CCR courses, so can't comment on current course content. I would be interested to hear from anyone currently teaching CCR, if the mantra "if in doubt bailout" is still fundamental to entry level courses or not.
The big issue abut delaying bailing out is that the in a lot of cases on CCR, it becomes progressively harder and harder to get off the loop.
One of the reasons that BOV have become much more available, is that, in the event of a CO2 issue, paranoia and judgment impediments aside. The desire to take another breath is automatic, and it is almost (if not) impossible to suppress this desire to take another breath if you are suffering from CO2 issues. Hence the practice of getting off the loop early if you suspect you have an issue.
With MOD1, the depth and amount of decompression penalty incurred on a dive should not impede a relatively speedy return to the surface. So there should be little need to extend the available gas, or optimise the decompression schedule, unlike the situation when you are looking at MOD3 level dives.