it's best to take it slow with verbs, because there're so many forms and conjugations you have to learn with each verb, so the form of the verb comes automatically.
like if i ask you what is the causative form of 'pay'(しはらう), you can automatically say it's しはらわせる(let/make/had someone pay) without thinking much. i doubt you can do so if you're learning 15 verbs a day
also, there're many similar forms of verbs, like ドアがしまっている is very similar to ドアがしめられている, both meaning 'the door is closed'. it's different from ドアをしめている, which means 'closing the door'. and there're a hell lot more stuff like this to learn.
かわる and かえる both mean 'change', but has completely different meaning. there're a lot more such similar verbs.
that's why it's better to take it a bit slow with verbs.