I have just reached my limit of suggested edits for the day when I noticed someone else has 21, when the limit is 20, how can this be?
If the post on which one of the edits was performed is deleted, it does not count against the total for the day, but still counts as progress in the queue.
There is another reason.
If someone suggests an edit on one of your own questions or answers, you can still approve or reject the suggested edit, even if you have reached the limit for the day.
I got 21 reviews on suggested edits one time because of this behavior.