Knowing when to end a crap surfing session is one of the most difficult challenges for the crap surfer.
You've screwed up your courage to get out there, often in very difficult conditions like two-foot waves; you've been out there; and...nothing's happened. How can you justify giving up yet again? How much crap surfing time is enough?
Crap surfing is very difficult to quantify, and cannot be measured in the ways that apply to regular surfing: number of waves caught, number of rides, fun had.
Nor can you measure that degree of pleasurable tiredness that comes from successful exertion of muscles in real surfing, since crap surfers rarely avail themselves of the muscles in their arms and legs and are generally unaware that they even have any. Crap surfing has no rhythm or momentum, no climax; just the monotony of failing over and over to do anything remotely related to real surfing. Here are some hints on knowing when to---mercifully---end a session.
You could attempt to quantify crap surfing in some ways, such as the number of gallons of water up your nose. I believe that in the U.K. a perfectly acceptable excuse to end a session would be that it's time for tea. In the U.S., breakfast, lunch or dinner would suffice.
Always stop and get out of the water if you're hungry---dedication to your sport is one thing, but there's no need to be a martyr. The sight of blood---yours or anyone else's---always ends a surf session honorably, but relying on this method is not recommended.
However, in many colder climates, the loss of feeling in hands, feet, or nose provides you with a legitimate excuse for going indoors, as, in warmer climates, does the loss of any appendage to a shark bite.
Real surfers don't end sessions for jellyfish stings and crap surfers shouldn't either. Do not wait for that "one last good wave to go in on", the one that you think you will finally ride; you've been waiting for that wave for years and it hasn't come yet.
If nothing else, darkness will always put an end to the most mortifying of sessions.
Whatever you do, never attempt to end a session gracefully, or with any semblance of dignity or style.That's for surfers who know what they're doing. Instead, crap surfers should only aspire to end gratefully; grateful that all your fingers and toes are intact, that you haven't bashed your head open, that you've survived one more day in the raging one-foot slop.