Like a lot of other people have mentioned, my free time is also at a premium (wife, kids, job, other non gaming hobbies, etc), but I was able to clear my schedule for a Petit LeMans 10 hr on iRacing this year. Just me and one other guy - someone I know in real life, which I think enhanced the fun factor. We did a lot of testing and a bit of strategizing but both of us were of the "let's just finish" mindset, which made it more fun than stressful.
We drove an LMP2 and, for reasons I don't understand, were placed in an LMP2 only split. That was probably the only bummer of the race because I was looking forward to the multiclass aspect and had even dedicated a fair amount of testing time to running multiclass practice sessions and sprint races to figure out the best overtake spots, etc.
The race itself was a lot of fun. I spun pretty badly on my very first stint and we ended up with something like 16 minutes of repairs. I felt terrible, but my buddy was cool about it and helped me diagnose what might have happened (even though at least part of the real answer was "nerves"). It turned out to be a blessing in disguise thought because over the next ~8hrs we steadily climbed the charts as other teams made goofs and we stayed clean. It was really rewarding to hand the car off in a higher position than I took it over in!
We had a chance for a really impressive (given our opening hours disaster) finish, but in our closing stint, in the pitch black someone spun in front of my buddy at possibly the worst place on the track and we had a massive collision that resulted in another long repair session. It was a major bummer because my buddy was really in the zone, clicking off blazing laps and really chewing up positions. Still, we managed to finish in our qualy position - after two decent sized wrecks, I was very happy with that!
I'm thinking/hoping we'll do it again next Oct...of course, if you asked my buddy for his impressions of endurance racing, he might say "I think they could be fun, but choose your teammates carefully - I got stuck doing a 10 hr race with a terrible driver and it SUCKED!"