Nope.
If you don't raise your bet in a high count until you win a hand, then you have left money on the table when you win that first hand.
You just won a small bet when you should have won a large bet.
As you say sometimes you don't win with large counts, so you win a hand with a small bet, raise your bet, and then lose the next hand.
Where are you? You are behind instead of even.
W/W is just as likely as L/L or W/L or L/W. Trying to raise/lower your bet by the results of the last hand doesn't work, no matter what the count is.
It is good that you are only entering in at positive counts, but if you are not tailoring your bet size to the count and your bankroll, and allowing results of previous hands to determine your bet size, you are not winning at the rate you could be.
Of course this all goes out the window if you are parlaying your bet in positive counts for purposes of cover. But remember, this cover has a cost attached to it.