I agree, but I often question the degree to which this is really true for someone with decades of lifting experience. If you've accumulated a lot of skill at getting muscle to fire in a basic "type" of movement pattern, how much does it really matter when you swap from one to another?
Example - You get really good at firing your lat in a one-arm machine row. You want to swap to a different one-arm machine row, for whatever reason...or a cable row, etc. Are the first few sessions on that "new" variation meaningfully less stimulative, in terms of hypertrophy?
I don't know for sure. It's almost a moot point for me, anyway, since I'm such a creature of habit that I'm going to repeat sessions week to week whether I think it's "optimal" or not. But I like to think that if I have to swap because my usual piece is taken, out of order, not available out of town, whatever - I'm still getting like 90+% of the stimulus I usually get.
We need to separate atrophy from neurological detraining.
I am not suggesting that muscle tissue wastes away after a few weeks of avoiding an exercise. However, the data on neuromuscular physiology shows that motor pattern efficiency decays rapidly when a specific movement is removed from your rotation.
For a serious BBer with decades of experience, this decay is the exact reason they experience a rapid, linear ramp-up in load and repetitions upon reintroducing an old exercise.
That rapid trajectory is the central nervous system rapidly restoring prior neural coordination, not the immediate synthesis of new skeletal muscle tissue.
The movement swap itself does not generate novel hypertrophy. What it can do is provide a psychological benefit, reinvigorating focus, effort, and adherence through novelty. It can itself be fun, and adherance is crucial as we all know.
That is a real, measurable mental benefit, but it shouldn't be misattributed to a physiological necessity for growth.
My position comes down to a strict filter of optimization. I will always side with the strategy that yields the highest return on investment for physical effort. I'm always focused on ROI.
This is the exact same reason I favor high-intensity, lower-volume training: extracting the highest-yielding productive reps early in the bout and leaving. It maximizes efficiency.
While many dislike this approach and or just don't enjoy it, it is likely the most time and energy efficient method. I fully acknowledge that's not what everyone is after.