Busier the lot the more waves you get.
1) More people in the lot = More non-surfers.
2) More people in the water = More people who can't really surf.
3) More mediocre surfers, the more you can shield yourself behind their numbers and their weaknesses and come charging out at the right time.

Surfed with far fewer people on Sunday but I had less waves b/c :
1) Most everyone knew roughly what they were doing and where to sit.
2) I blew a few, lost my confidence and people capitalized on this.
3) I'm self-conscious, forgot to take my CBD and had performance anxiety. This would happen less in a thick crowd.
Conclusion:
Best case scenarios is 3 buds sharing a peak. One surfing, one sitting on it and one paddling back out.
Second best case: surfing alone
Third best case: a thick clueless crowd with shifty peaks.
Fourth best: mellow, competent crowd on a defined take off spot.
The real best case is: Sunday Evenings on a Twin Fin Midlength. It is not a time or place or even a state of mind. It is everything.
Pink Floyd and Single Fin Logs.