Gravity and Weight training as of now has almost little to no use when you are higher levels, so I think it needs a revamp in the next update or the update after.
Gravity/Weight Training should have a system that gives TP depending on your level, and this would work by walking around in said gravity/weight. For example, if your stat decrease is 9%, you will get about 1,000 tp per minute when you are dbc lvl 100 or something. Or if the training weights are higher than your own stats, it will give more tp per minute every 16 blocks you walk. Depending on how far you walk your weight gain tp will increase the more you have walk around in it. This could improve training to be a little more efficient, but who really knows.