It should be literally impossible for 1 person of a $20 billion 45.000 employee company to review all expenses in a way that allows to discover inefficiencies / potential savings.
Lets go crazy here and say that the CFO works 16h/day 7d/week and can allocate 50% of his time to this reviewing expenses-effort. Lets be crazy and assume he can go through this process at a rate of 10 seconds / bill (=he can probably identify recurring bills which don't need to be rechecked, etc).
He would be able to process 20k expenses/week at that pace. I think Tesla's actual total number of expenses/week are far higher, like at least 3x higher, probably at least 5x. And my assumption that the CFO of a company like Tesla can allocate 50% of his time to something low mgmt should be doing, is of course crazy as well. And working 112 hours weeks might be optimistic, too.
Also lol@saying you have 10 months left to 45.000 employees a few weeks after raising money. 10 months seems accurate though? He's not being his optimistic self?