Terms/definitions for beginners/lurkers:

6RM for a given exercise/weight combination, you can only perform 6 reps, even if a millionaire offered you a briefcase full of gold bars to hit that 7th rep.

2RIR means 2 "reps in reserve" which means you finish a set 2 reps prior to failure. For example you stop at 8 reps, but you could have gotten 10.

By default, I workout in the mornings about 2-3 hours after waking up. This weird paradox I've been experiencing at the gym all year on my intentionally-light training sessions (i.e. when I want to preserve maximum mental bandwidth for a cognitively demanding task later that day or the next day) is similar in spirit to the following empirical paradox:

• Parkinson's Law states that work expands to fill the time available for its completion

It's like my brain down-regulates my ability to summon maximum strength output, which means if I want to leave 2 reps in reserve, I now must subtract 2 reps from the 4RM, which on paper makes it seem like I did 2 of my 6RM with 2RIR rather than 4RIR. It hurts my brain and makes zero sense from a logic/math perspective. I listen to tons of pop-science fitness podcasts, including Huberman. Seemingly, the key concept is intent/pacing and how your intent/pacing drives force production via a neurophysiological explanation that reads like technobabble nonsense when I asked chatGPT about it.

My first question is does this even happen to other people? Or am I just the unlucky one?

My second question is how to fix this problem? Are there any "mental form cues" that can restore my true 6RM? I do everything the exact same way. My pre-gym routine is always the same. (pre-workout powder similar, loud music while driving to the gym, mentally pumping myself up, etc..)

In fact, on my own gym notes, I document whenever my numbers are low (such as a poor night's sleep or had to do my beekeeping in 95-degree summer heat earlier that day). So for my light sessions, I just lie about 2RIR in my workout log rather than blaming "magical, mysterious process which shrank my 6RM to 4RM today".

Update -- upon feeding this post into ai, I should make a possible correction. It's plausible that I could do 2 more reps on my "light days" but I'm in the same agony doing my 4th rep on a light day as my 6th rep on a normal day. So I guess what my question truly should ask is why does my brain dump loads of physical pain/agony into my consciousness on the 4th rep of my light days but waits until the 6th rep on my normal days? And more importantly -- how to fix this stupid agony-dumping mechanism? I hate the fact that on my light days, I walk out of the gym equally mentally exhausted as my normal days, even though I trained at much lower intensity & lower volume. I don't compensate by doing more sets or cutting my rest time between sets. I don't choose my light days because I'm feeling less capable. I choose my light days based on future cognitive tasks and sparing CNS fatigue.

Update2 -- I believe it is worth noting that I should actually record this phenomenon to test whether my claims and assumptions are actually true. I should compare my rep quality because knowingly doing fewer reps might make me perform the concentric phase more explosively, and with slower, perfectly controlled eccentric phase. This can only be done with recording myself on my phone's video camera, which I plan to do. I already have a dozen or so recordings of "normal days" performing the shoulder press, so I simply need to record my rep quality on a light day's workout.