The issue isn’t that Grover explains things as they go. It’s that the only reason he’s explaining it is clearly the audience. In the original books you’ll find people explaining things to Percy constantly because Percy is the reader’s eyes and ears. Percy represents (like an Ambassador) the reader and so he learns along with us. It’s the most used way to drop information.
So, of course, when they announced that the Disney Plus Percy Jackson series was starting at Christmas I wanted to create a dish for the occasion. Originally it was intended to come out at Christmas, when it started, but due to the time it took to plan and prepare the different parts I didn’t manage to complete it for then. Instead I decided to get it ready for near the end of the series, as a celebration of the full Series/Season 1.
The Literary Onion 