Yang Cheng Fu and the other famous historical tai chi instructors did not collect forms and styles.
They trained one form and focussed on that.

Form collecting is a modern habit which arises when a student is unwilling to commit the necessary practice to mastering a form.
In short, the student gets bored.

A form is a complete record and repository of the system.
It contains every strategy, skill, movement required to gain a good sense of the art.