You can never go wrong with bringing extra loops.. Worst case scenario is that you bring them home unused, ready to go out again. I had to cut the base of a 24 inch Ash stump.. Brought the Echo CS 800P, with a 27 inch bar. Just out of an abundance of caution, I brought the 3 extra loops.
Darn!! 1st loop ( on the saw) .. not even 1/4 through the stump, and I see sparks coming out of the cut.. Followed immediately by dust, not chips.. Crap.. with the crew standing around, by the hour, there's no way I'm gonna sharpen.. Toss on a spare loop and back at it..
Cut another 1/8th into the stump.. Same thing. Sparks and dull again.. It took all 4 loops to get through the stump. When we popped the top of the stump off, we found that I'd hit bullets, and nails and screws from mounting kids toys.
If I wouldn't have had the spare loops, the time for paying the crew, or having to come back the next day, would have eaten into the profitability of the job..
Still, after having got into metal, after getting home, it was a couple of hours with the bench grinder to return the loops to usable condition.
Bring extra loops, and a spare bar.. What's the worst that could happen?