The busiest course I ever saw was the Las Vegas muni - over 100K annually. Of course, at least 364 play days, and usually played to near capacity of 300 players per day. Actually, I did the math and it looks like the average is 274 players per day.
However, 300 is usually considered the absolute number of golfers per day, and at one time, many public courses got that on weekends, and maybe half of that on other days. One rule of thumb is your 5 days of weekday play typically equal your weekend play.
In Dallas, popular public courses can play up to 65K in a 12 month season. Most were more like 45K in the early 2000s but dropped during recessions to 30K or less. Post covid they are spiking back up.
You can estimate the max capacity of a course per month as 30 days minus average rain days, times hours of operation, and typical number of foursomes per hour (usually a max of 7, should be less, like 5-6 groups per hour) Of course, the pro or GM should probably have a record of play, but those are often surprisingly inaccurate, and many don't differentiate between 9 hole rounds.