I'm currently using kettlebell 12 kg for warmup and 20 kg for workout. I'm able to do 40-50 swings with 20kg.
Now I'm considering progressing to heavier one and I'm in doubt should I go for 28 kg or 32 kg (and how many swings should I be able to do before trying heavier one).
Kettlebells that are on the sale where I live progress each 4 kg, and for commercial gym it makes sense to have all weights, but at home, I'm limited both with available place and financial means so I'm looking for reasonable step to progress that would be a compromise between making too large gap and overpaying.
Is a progress from 20 kg to 32 kg too extreme, or I'm still on the safe side (so that I don't risk damage by switching to too heavy weight too soon)? Is there any rule of the thumb for maximal weight difference when switching to heavier kettlebells, similar to 10% rule for weekly running mileage?