According to TURTLE :

So you say there could be a small Nano-second longer for a double pole breaker
to trip on one side and no amps on the other than a single pole breaker and no
other breaker attached.

A nano-second is a very short time for a mechanical device. I'd suggest
it might make a 1 or 2 millisecond difference in trip time. Which might
be 10% of the trip time at max fault (20,000A), but fractional percentages
of more usual trips (10s of seconds).

I seen this on a old country bar in the middle of no where. They did not have
any singles at all but all doubles and when needing a single they just used 1
leg of the double. This place is fixing to burn soon.

But not because they were using one side of duals tho. It's likely to be
a sloppy job in other MUCH more hazardous ways. Ie: did they use zip
cord in places because they ran out of building wire too...?
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.