Character & Pet's stats, increase faster once they have a skill at 100.0 or higher as long as that skill is used during the training process, you can also gain any of the 3 stats from a single skill, as opposed to the two that normally correspond with said skill.
Every skill has two stats associated with it
for example Musicianship = Dex & Int However, once Musicianship hits 100.0 (real skill - even if it's locked), you would then be able to gain Str from playing an instrument as well. some holds true for any skill, as long as there's a skill-check.
I always train my pets & characters stats with 'Resisting Spells', very fast with spellbinders or paralyze fields. (Spellbinders are a bit faster, if you get 10 or more
)