I would say it is up to you and your specific goals for certain words/characters. The “too easy” option can be used if you want the system to schedule the card even further out than “got it” would. The advanced grading system was designed to give you a little more control over the scheduling.
Specifically, the “too easy” option allows you to push cards that you feel confident about further out in the SRS scheduling. Here is a document that explains how our SRS system works if you would like to read a little bit more about it.