If R1 buys a sub, they waste 6 IPC. If they have average or worse dice in taking WR and Ukraine, you should seriously consider forgoing africa and full-pressing Russia. Maybe attempt to take and hold WR, as in case blue:
But I found that just forgoing africa and attempting a take and hold of ukraine can also work wonders. Use your transport to take 2 units off africa, and land in europe. Build mainly tanks and a few infantry.
I prefer a 6 inf, 2 arm, 1 bomber or 3 inf, 1 art, 3 arm, 1 bomber. The added punch to the Luftwaffe can be really helpful in preventing the UK from doing any landings on UK1.
Usually the Algeria landing is prevented until US1 or UK2, which gives the Germans 1 more round to bring troops to Africa (if Russia hasn’t bought a sub on R1, that is). And if you manage to sink the UK fleet on G2 then you won’t have to worry much from the UK/US for the next turns. If the UK buys 1 AC and 2 DDs, then they’ll have those plus 2 fighters and the US cruiser for defense, possibly also the R sub, depending on how that battle went. You’ll have 2 subs, 2 fighters and 2 bombers, if the 3rd sub survived the battle up SZ1 (by losing the fighter instead of the sub, for instance) then it is possible to sink all Allied ships.