It’s not a hard and fast rule. I’ll share some info to help you with your decision though.
I do think that giving your body enough break between rounds is beneficial to give your body some time recovering from the taxing fat loss process. Despite how wonderful and amazing the hCG protocol is, it’s still an extreme measure to take with our bodies. Giving it a lengthy time to recover to me is an important facet of preventing things like adrenal fatigue and thyroid issues from setting in from too much dieting back to back.
Personally, I think even the 6 weeks is rather short for a break. At the same time, I do understand if you have a lot to lose, you don’t want to waste too much time or lose your momentum. In some cases, it has definitely worked out to either do longer rounds than usual or to take shorter breaks than usual.
Here are a few posts to help you decide:
Extended hCG Rounds and Shorter Breaks – positive experiences with these
I hope that helps!