Glyfair
Explorer
There are some items that have charges, I don't recall seeing that before but I could be wrong. These are charges per day and different abilities cost different charges.
That makes sense. The PHB series was supposedly designed so that more complicated classes come later. This would follow the pattern in that more complicated magic items come later.
Note I am not saying they are hard to understand. But tracking different numbers of charges certainly adds extra complexity in more things to track at the table (sort of like psi points).