The Summer Solstice is the perfect day to complete 54 holes in one day. Become a member of Club 54. Membership is available at Club54.us.

Playing a ton of golf is really just a function of how open the golf course is. I played 54 in a day in Myrtle Beach back in May on 3 different courses. Riding in a cart, it really shouldn't take much more than 2 hours to play 18 if you're a single.
I also played 72 in a day on the RTJ Trail in Birmingham, walked the first 54 (at Oxmoor Valley) and rode the final 18 at Ross Bridge.
I've also done Colton's Hundred Hole Hike and I played the full 100 holes at the RTJ site in Mobile, AL, getting about 4 hours cut out in the middle of the day from a thunderstorm.
I knew a guy who did a golf marathon using a cart...he played from daylight until dark, averaging about 45 minutes per 18...played over 300 holes in a day.

Try Midnigth golf in Norway under the midnigth sun
https://www.golfbreaks.com/lofoten-links-golf-club

I was in Wisconsin a few weeks ago and played The Ridges Golf Course and 2 hours later I played the Snndbox as Sand Valley Resort for 36 holes my first time ever doing that ! So I have now for filled a bucket list of playing 36 holes in one day

My friend, Ken Peterson of Coon Rapids, Minnesota, has played a golf marathon each year for nearly a decade to raise money for the Autism Society of Minnesota. This year, he played 171 holes in one day. He has raised nearly $50,00 over the duration of his marathons.

About 30 years ago I participated in the Longest Day of Golf to raise money for the Canadian Cancer Society. We teed off at sun up and played until sunset. There were 4 golfers with substitutes for lunch and dinner breaks. We did not keep score and just hit the ball and went on. We were also given power carts. The team completed 16 holes and I personally played 180 holes. Needless to say I had to take a couple of days off of work. I was in my 30's at the time and had a great time but it was still the hardest thing I have ever done. I also won a trip to Bermuda in a draw based on the amount of money raised. I believe it was 1 ballot for every $100.00 dollars raised. I had 5 ballots.

I play at least 2 rounds a day when I play. My method is to tee off in the first or second group in the morning. Then I'm guaranteed my second round will be within 3 hours of my first round. Breakfast is served after the first turn. The most holes I played was decades ago on a 4th of July weekend carrying with a friend (54 holes). I wasn't aware of the extended daylight in Michigan. Now it's on my list for a June golf trip. Thanks Brandon.

Shooting for 80 tomorrow in a Dawn2Dusk charity event... *fingers crossed*

Years ago did the 100 holes of golf for charity - raised $2500 on my own. Never again (too old now), but took me several days for the swelling to subside! Good fun, worthy cause, but too much!
Golf buddy trips to northern Michigan used to be 54 holes for 3 days - again not any more. Now more like; 27 day one, 36 day two, then 18 or 27 and a 4 hour drive back home!