The log chart is a good resource and can be found in the Sherrill catalogue or on pdf but logs are not always uniform or consistent and may have a void cavity in them or concrete, who knows. Shock loads, like sheeaht....happens too.
The biggest factor is the experience and common sense and intelligence of the players involved in the pick. I usually start small and work up when I am hooking up a piece anything questionable is gonna get a nod from the crane op. The person hooking up or the crane op should have worked up in experience that put him on this job site making these decisions as well. More so when booming over a house or some other delicate target extra care is a no brainer. That piece cut in half would have saved the day and taken maybe another 15 minutes.
I agree especially in this case where as you mentioned 15 minutes more would of saved the day. Also I agree most is common sense, however I've been on a few jobs were someone want to keep the logs a certain length. Also while not tree related I've hauled many loads where the rigger on the delivery end either doesn't have a big enough crane or looks to me as if I should know his job better then him and or how far we can push his crane. My friends crane has a manual that is very broad and not specific towards his particuliar crane. Luckily the computer and engineers safegaurds does most of the thinking but it would be nice to have better manuals. It's like rebuilding a car using a Chilton manual,
"Take motor out, replace bearings, rings, and gaskets, put motor in engine bay and attach motor mounts, coolant, fuel, and electrical lines. You are now done" Attached is pics of a 1984 Buick Century while your trying to rebuild a 2000 Chevy.
My friend is pretty cautious with his, and aside from what I posted above, we or he hasn't had any other close calls that I know of. Not that I'm big on regulations and not that I'm implying that there should be but it does kind of surprise me that you can buy and operate these big cranes with no formal license or certificate.
P.S. Thanks for the resources.