The string keep a nice compact firm shape while grilling.
This is the problem with any recipe that gives a time and temp. The variability in ovens, bbq's and thermometers is wild.
Many BBQ's have cheap shit thermometers, if you have an upper rack, maybe attached to the lid, you could put a decent oven thermometer there and check it once in a while, once you get the burners set to a stable temp, it should be good.
A friend swears by his probe thermometer ( probe in the meat, cable to a readout outside his Q.
I take my chx to 170.
Glad it tasted alright.

