Definitely not a pro here like Bob.
Since you asked. Usually current pace, elapsed time and distance. I may have a 2nd screen for other metrics. I may not. I set it to manual scroll if I'm curious to dip into that data during a race. Usually not, actually rarely. Maybe add elevation gain in a hilly course or % grade on a bike.
I make sure auto pause is off. I manually hit the course splits. They vouched for it. Not garmin. I can allow both to be off in any measure. Who cares?
Mostly I need it to keep from going too fast, or to reassure myself that the exhaustion that I feel is warranted on the effort I'm running for this particular race at this time. It's a backup systems check. I use to track HR more accurately in training. I've not studied it in my racing. The fidelity of my strap is poor. Maybe it needs a battery.
FWIW I only check a couple of times in a 10k or half. Sometimes never.
YMMV