It’s always hard to spend more then your opponent. But if the allies are earning more then Germany (ie America + England >= Germany’s income + Russia) and Germany’s got 3 smaller stacks of 15-25 units in E. Europe, Germany and W. Europe, it can work out.
Bear in mind, that in the circumstances I, personally, would use it, Germany’s earning in the 30s to low 40s, so losing 10 infantry a round is almost their entire purchase.
For example, Germany has 20 units: 15 Infantry, 3 Armor, 2 Fighters.
England attacks with 4 Infantry, 4 Armor and a Battleship.
Result: Germany down 3 to 5 infantry (1-2 rounds of combat)
America attacks with 4 Infantry, 4 Armor and a Battleship. (Takes 4X4 transport system)
Result: Germany down 3 to 5 infantry (1-2 rounds of combat)
That’s just average, you may get lucky or unlucky. Either way, however, Germany’s lost a huge chunk of their army and cannot stack sufficiently.
Now, I’m of course assuming those are the numbers. There are circumstances when it would work a lot better or a low worse.
What if Germany only had 10 infantry, 3 armor, 2 fighters? Or no fighters and only the infantry and armor?
You have to make conscious decisions. But the idea is to bleed Germany. It’s like SBRing only you take more away from Germany and don’t risk high value bombers!