Delta variations in length after hitting new max

For guys that have been doing PE for awhile targeting length and measuring often. How often have you seen length gains decrease and then increase and what are the deltas that have been observed? For me, since I’ve done PE starting in Aug I’ve noticed that my BPSFL has varied by up to a CM where I hit a new length gain max and then a week or two later I’m a few MM’s shorter than that. For example, I hit a new BPFSL of 20CM and then a week later it’ll be 19.7CM and then go back and forth between those two for weeks at a time.

I’m also relatively new to PE. I’ve seen variations of BPFSL of 1/8 inch up and down. My hunch is this is directly related to the quality of warming, stretching and jelqing during the session and their effect on the plasticity of tissues. I’m following the newbie routine. While we’re eager to check for increased results after every PE session, you might see the trend with greater consistency by measuring only after 4 or 5 sessions. Good luck!