As far as having WUs hanging around.
If you are looking for prime numbers, it is important to set that to 0.00 both store at least and the other additional one to 0.00 too
Reason is to get credit as founder of the prime, you have to turn yours in first. There is someone else doing that same WU. You want them to turn it in 2nd, they will be the "double-checker" also where it asks for your name, put it in there and check the box to let them report the prime for you. Then your name will be in the book of largest 5000 primes found.
Also doing LLR units you want hyperthread off. Doing sieve, HT can be on.
In a sieve challenge it is not a bad idea to have a few extra WUs waiting, just in case you lose internet connection. You still have work to do.