How does this stand re the Russians?
The other part of the plan was the assumption that the Russians would be so slow to mobilize, partly because that their railways were so relatively poor, that France could be beaten before there were any serious Russian invasion of Prussia.
Also, is the SP mandatory? Does your setup allow Germany to choose another plan such as concentrating on Russia first? (I’ve suggested a secret mobilization turn before war breaks out, where each power writes down non-combat moves in secret. They are then revealed simultaneously and units sent where they’re ordered. All units in this case will start in their peacetime depots, that is pretty evenly distributed among home tts.)
It could be argued that the SP was in effect a win-or-nothing strategy: if it succeeded Germany had effectively won the war, if it didn’t the best they could hope for was a favourable armistice.