Does relieving the "volatility" of supply rolls make Afrika Korps better for the Germans?
You narrowly avoided a massive hoodwink.

The game runs in fortnightly turns from March '41 through October '42, a total of 20 months and 40 turns.

By the Supply Rules, the German supply expectation is:
- Apr. '41 through Jun. '41 ( 6 turns @ 4/6) =  4
- Jul. '41 through Nov. '41 (10 turns @ 3/6) =  5
- Dec. '41 through Oct. '42 (24 turns # 5/6) = 20
for a total expectation of 29 supply.

Your friend offered you a guaranteed schedule for only 40 * 4/6 = 26.7 supply.

You would have found yourself in supply difficulty through the final turns of the game, deprived of 2.3 supply relative to a normal supply expectation.

I doubt that a 1.6 additional supply expectation from July through November '41 would have compensated for the reduction by 4.3 through the final half of the game.

Yes, I have simplified the arithmetic slightly by ignoring the guaranteed supply on April '41 I turn - which adds 0.33 to the expectation in both scenarios - a wash