Don't think its a real problem ---- time limit. Unless the trap is getting to full w/shb to be effective. That has not been my experience!!! Two weeks I've not checked them for that long --- several probably ok. Depends on shb population, they are small and would take alot to fill trap. There's not a bait so the FGMO doesn't lose it's potency or anything.
I have done inspection and see ten or so flee from the trap covered in oil, but I think once covered it breaks them down and kills them. Some folks spray FGMO on thier end bars, I tried it but didn't like it!