sleep $[RANDOM/3600] works everywhere without requiring jot/seq etc. on BSD/Mac/Linux.
This might be platform dependent though, I can't find any standard RAND_MAX in bash so it's difficult to make this work everywhere.
sleep $(( 0x$(xxd -l2 -p /dev/random) * 3600 / 65536 )) s/\//\\%/
yeah. sleep $[RANDOM\%3600]