In reply to stp:
Apologies I should have been a bit more specific and said in context for bouldering, where simply you don't get enough time on the rock for fingers to wither and fail before something else pops like a foot and your off. Do a long session of projecting and you will find its your core that goes first, the body positions, footholds and technique are completely different outside to indoors. I suppose it's different for routes where you have more opportunities for rests.
Regarding training strength on a finger board, try 4-5 seconds on with 12 seconds off but with a very heavy load added. Eva Lopez's maximum added weight, minimum edge width protocol outlined in the link is very good and has worked for me in the past.
The protocol I used was add a large load and hang off a one finger pad deep edge in half crimp for 10 seconds. You need to calibrate the load so that you feel that you would fail at 13 seconds but you get off at 10 seconds.
Do low number of reps, 1-2 per set with a good 3-4min break.
Once you start hitting 50-60kg added weight the harness is really uncomfortable, switch to one handed hangs and build up to adding weight.
I didn't find the minimum edge but very useful accept to reinforce my mind how truly small an edge you can hang off if you will yourself to do so.
I would also advocate getting a small sling and some weights and hanging weights off each finger in a half crimp to figure out what is and is not your weak point. Difference in a fingers length compared to its neighbors can have a massive influence on how you use your hand and how strong the fingers get as you will have a favoured grip position. Once you figured this out, strengthening the weakest link in the chain will have a big difference, bigger than trying to eek out more strength out of strong fingers.
Tom Randal's TrainingBeta podcast is pretty good at helping you get your head around the different energy systems which support forearm performance in the different climbing disciplines and is well worth the listen.
Good luck Happy crimpers,