[USA] deducting inventory as an expense

Everywhere I look half the people say you can deduct inventory and half say you can not.

I am small business owner and even spoke to my accountant which he said I can. I do not necessarily keep track of my inventory because naturally we have a pretty fast turn over rate for selling. The thing is that we also do not keep a beginning inventory then update it quarterly to be honest I feel like this is quite mind numbing since I am not even sure exactly how I would do this anyways

Do I check my inventory

MARCH 31

MAY 31

AUG 31

AND lastly DEC 31?

How about if I did not have time MARCH 31, but then purchased stock like a day later and accidentally added it in wouldn't it throw my books off?

For example March 31 (30k inventory) this would be the beginning before the next quarter then April 1st I finally do inventory but got 20k inventory since last night so now I have 50k inventory, I would then deduct 50k inventory from my sales lets say 55k so It would look like I made 5k for this quarter.

Anyways goes to say this is why I prefer the cash method because I rather just expense now and deal with my income later.

What is everyone else doing?