Dave, it all depends on your goals... You can run 5/3/1 BBB standard, or take the challenge. The standard BBB template keeps you at 40-60% of your TM and it meant to address a weakness and also help put on size. Some exercises you might find are easy to do 5x10 @ 50% while others you might find need to be more or less than that.
The challenge, however, is to hit 5x10 @ 70% by month 3 - which is not easy... Let's say you have a 405 pound training max on the squat and by month 3 that training max is now 425, your 5s week looks like this:
Squat 5s week:
BBB 70% 10x5 @ 295 - that's 50, 300 pound squats after your main work sets.
If you left it at 50%, the BBB sets would be 215 pounds - a lot easier to manage than 295.
So it's up to you, take the challenge, or stick with the standard. I'm 38 years old and run the standard, but I've done the challenge before and believe me, month 3 takes a huge set of balls and even more food to get through and recover from.