Best Betting Style for SD

Experienced advantage players, please kindly comment:

I've found a local SD game that usually deals about 5 to 6 hands when it's heads up, sometimes even deeper pen depending on the dealer. Conditions are favorable. I'm using a 1 to 4 spread: betting 1 unit at TC+1; 2 units @ TC+2; 3 units @ TC+3; 4 units @ TC+4.

Anything above TC+4 I spread to 2 hands of 4 units.

What are thoughts on this betting spread style? Is there a way I could tweak this to be even better? I have no idea what the ROR involved with this spread is, but if any of the mathematically inclined want to take a stab at it I'd be most grateful.

Thanks to any and all who may proffer constructive feedback on the above. I greatly appreciate it.

Very Respectfully,
Ian