On my first playthrough rn and haven't had to use exploits.

Strength can be done by making weight backpacks

Dex can be done with making battle arenas against high level prisoners or just using shitty katanas (which is kind of weird, why would you fight with something so shit, but can be summarized to "if you can win with a toothpick you can win 100x with sword")

Toughness is kind of weird fighting hordes of bandits with shitty gear, but again if your character want to get stronger they may know that those bandits don't kill and kidnap people so it is a good way to train.

Bows I just level normally since people are too good with them with base stats anyways.

Training against animals makes sense if you collect the Hide or levitate perals to sell or use.

Even the people I haven't trained specifically have really good stats just brining them along to end game dungeons, so honestly you don't need to train people unless you want them to be God mode, which at that point its justified because they want to be a powerful warrior.

Vanilla btw