I go thru phases where I want to have a strict program ( 85% of the time ) and interspersed with periods of "do big lifts, and figure out the rep/set/weight scheme once I get out there". This grew out of the former.

While mixing high volume into a mostly 3x5 or 3x3 straight sets, and 5x5 ramped sets scheme/program, I wanted to have a standard for those 5x10 and 8x8 days as well.

Doc you're right about it being Actuarial. In this case that means it's better to be precisely wrong than haphazardly accurate.

Ken, for the singles, each additional set lowers the weight less, but rounding it does look like 1.4% atleast for this 10x5 chart.

Extending the formula (yes it's a formula I derived(?) ) to 10x10, you get 54.5%. That is lower than the %60 I see out on the interwebz. For me, I've tended to fade more with high reps relatvie to the standard charts (in other words the 2-4 RMs belie my 10RM)

Clearly, another dimension is Rest periods. Subconsciously, this fits a "Rest more for lower Rep ranges", as that is how most operate. No one goes into a 7x7 thinking, I'll rest 5 minutes between sets. Some reasonable checks were such as "5x2 can handle more weight on the bar than 2x5", and likewise with similar pairings.

Finally, I figured there is

1a. I started the 1 set formula keeping in mind the (37-R)/36 one I've used/seen around. My values end up close to that one.

1. Within each set range, A diminshing impact of each addtional rep

2. Within each rep range, A diminshing impact of each addtional set

3. That said, the formula is also set so that if you compare the %'s between two colums or rows, it's clear that the impact of an additonal rep/set causes a bigger change in the higher one... an example

Considers the %s for 3x5 vs 3x6 as we add a set

For the 5 reps, we drop 1.9%, from 83.5 to 81.6

For the 6 reps, we drop 2.1%, from 80.6 to 78.5

All 3 of those principles make sense.

I might be a nerd