Anyways,
I heard that if you lost 10 to 15% of your strength after training a movement, you have already sufficiently stimulated the muscles enough to promote strength and hypertrophy.
For example, for bench press:
225 pounds for 3 sets of 10 reps. The first two sets are fairly difficult but all 10 reps are completed. But the third set I only got 8 reps. So I drop the weight down to 202.5 pounds (10% less of 225) and rest for a few minutes. If I cannot complete the next set of 10 reps with 202.5 pounds, this means I lost 10% of my strength therefore I’m done for the day.
IFBB pro Greg doucette, Charles Poliquin and Jeff Cavalier mentioned this but I haven’t seen any studies that prove this.
Given the highly varied nature of individual response to training stimulus, any one strategy is unlikely to be effective for everyone across the board. Also, I tend to be highly skeptical of anything with Jeff Cavalier’s name appended to it.
It’s reasonable to autoregulate dosage based on fatigue. What you’re describing sounds a lot like the fatigue percents that Mike T used to use (I think he’s mostly stopped).
There are a couple clear errors with what you’re suggesting. The volume needed to maximally stimulate a strength increase vs hypertrophy are probably different. Rest times need to be consistent for this approach to have any utility, and one fatigue percent doesn’t fit all rest times. If you are performing sets at a high RIR (and without a velocity tracker) it’s really hard to determine your fatigue. If you are performing multiple exercises for the same muscle in one session then this rule gets really messy.
The three people you named are not good sources of info IMO. It’s interesting that none have provided evidence alongside this claim. I googled “Critical Drop-off Point” and it appears Poliquin’s explanation has some depth to it, but really I think this is a made up rule of thumb. If you are interested in using it I think it has potential but will likely benefit from you experimenting with different fatigue percents, rest times, relative intensities, and rep ranges and then making tweaks or moving on if it doesn’t prove useful.