Penetration of course!
Penetration gives one a greater assessment of the ratio of tens to low cards.
One could do Thorp's idea of double-up/matingale IF the count stays reasonably high; shuffling will neutralize this most of the time!
But I have to admit, even though some counters want many more hands due to a faster dealer and less talking and stalling the game, I like slow dealers where counting can be as exact as possible. fast dealers wear me out!
But penetration semms to be greatest among novice dealers and worst among Asian women or some older established dealers.
Asians seem to be more loyal to the casino by shuffling early in SD when a few too many lil cars show.
It's been said on this board, 'that American Born asians aren't as bad'; but I'm not sure I buy this.