Which char do you play? 40 hours in training is really not much, so dont worry about that. I have like over 400 hours in practice mode and there is still so much to learn.
Viola, more than any other character, lives from her long combos. So make sure that you feel confident about executing them. Check out her combo thread in case you haven't already: http://calibur.8wayrun.com/threads/viola-combos.14657/
Its also important to not try to go for the most impractical combos just because they do much dmg. Try to find combo starters that you can land easily and expand on them.
Her biggest weakness is her short range, so you need to be well aware of how spacing works. Check out this excellent article by DrakeAldan: http://calibur.8wayrun.com/threads/spacing-lines-in-the-sand.14615/
(you should read his other articles as well, while you are at it)