>Based on previous experiments (example: old version of
>shapeshift spell/skill), I'm pretty sure everyone would just
>go off and spam these for a few hundred hours before 'really'
>playing their characters, if that's what they had to do to be
>'optimally effective'. Most likely complaining about it all
>the while.

Have everyone improve on skills via both hours and levels based on int. E.g. you get an improvement of int * 5 randomly distributed every level and int / 10 improvements every hour.

OR

The 75% cap on practicing at the guildmaster increases with level and hours. Practices are used with diminishing returns e. g. your first practice gives you int * 2 skill, then int, int / 2 etc. You can put the practices in anytime, but your skill can only go as high as your hour and level-based cap.

Note: All numbers given are for demonstration purposes only and would would produce a horrible result, in practice.