10 tops bets are not enough. What if you are down a few large bets and then get a hand where you split and re-split with doubles? If you split 4 times and double on each you could need 8 top bets on a single hand. You do not want to be in a situation where you miss a double on a 10 or 11 vs a dealer stiff in a plus count with your top bet out. If the dealer then pulls a 21 (I am talking from experience here ) you are going to need more chips to continue playing in the plus count, as you never want to leave a table when you have the advantage.