On 4x4, I use 6 at a time for the first 6 edges then chain solve the rest. I really like that method and wanted to use it on my 5x5 but I see a few reasons why it's not the best to use.
The main reason I like 6 at a time on 4x4 is because after you finish your first six, all the middle layer edges are solved and you don't need to check there for your next edge. On 5x5 these edge groups aren't fully solved so you'll still need to be checking there. Also, the best 5x5 edge cases(imo) are when you're slicing into a wing of the same colors, with 6 at a time these cases just get in the way and ruin the rhythm.
Plus, what MTGjumper said is true, if you had a case like this but the wing came later in the chain, you're kind of screwed because you don't have anything to pair it with. This can also be a problem with your first pair. On the 4x4 if the first pair you pick is actually just two swapped pairs, you can do a slice the other way to quickly solve one and continue(or start) the chain. If you got this case on the 5x5, 50% of the time you wont be able to do this first quick pair and you'd really just have to start a new chain.
As far as 5x5 edges go, you're really not going to be getting anything much faster than freestyle or AvG.
