[2019] Alaea Crabs, or AFK rocks in general

Ok, so im making this post because i made a calculator for mining, using all of the rather detailed formulas provided to us by jagex. Originally, this was only to provide me an estimate of my ores, but I also added in an area to calculate exp/hr, and I found a possible problem.

Upon accounting for every piece of gear, avg pickaxe hit chance, and even adjusting for critical hits, my calculator predicts about 400k exp an hour on alaea. Actual in game r metrics shows 330-370k, depending on recent criticals. Out of game r metrics also shows ~330k-335k exp an hour (the log for the actual exp gained for the hour) time searching for new crabs is minimal, sub 5 mins every 30mins to 1hr usually.

Now, I thought i messed up my math, but checking and rechecking I could find an error. But today, I think I found it. If i remove the +25% damage bonus for full stamina, then my calculator predicts 335k exp/hr. My understanding was that alaea and seren stones, because they are AFK friendly were not supposed to deplete your stamina, and therefore function as if you are at 100% stamina, so no need to click. In game it shows green sparks on mining, indicating full stamina, so Im a little confused as to if this is actually the issue.

Anyway, what I want to know is are we supposed to be getting the 25% for full stamina? Are we? is there an error in my calculator somewhere?

I'm linking a copy of my spreadsheet below, but be warned its a bit of a mess.

Id appreciate a jmod looking into this or clarifying this, but I doubt ill get a response.

Spreadsheet: https://docs.google.com/spreadsheets/d/1bSFNA26QYuVFCByZPtDd555KVuXQ9HFiqTvjefcoG6M/edit?usp=sharing