Jesus , that's one hell of a lot of bets, I've done around 80 pages of settled/lapsed/cancelled bets today but 438 pages is mental
I'd certainly start to keep a track of your transactions and comms paid if you're doing that many bets a day as it could get very costly if you don't generate any comms. I'd guess your arbing is keeping the charges in check at the moment so if there are any arb free days it'd be worth keeping an eye on the comms and transactions. Sadly as you'd expect Betfair don't have any easy way of showing you your current figures.