The easy answer is yes!
10g preworkout is optimal.
That being said, 5g may be enough, depending on your body and workload.
If you have a way to check your blood nitrogen levels to see how much muscle wasting that you are going through, then you may better answer that questions. I had some labs yesterday after my workout and during my fast, and my nitrogen levels were relatively low-normal, which is friggin fantastic because I wasn't burning any unnecessary muscle post workout and with only BCAA's.
BCAA's are for real, and they work. That is one supplement that I swear by. Try Formutech's Perform BCAA's or USPLabs Modern BCAA+.