Using PE as a valuation basis for companies that go through a...

Using PE as a valuation basis for companies that go through a boom/bust cycle is flawed. There is no way you can accurately predict future lithium prices based on a historical PE at any point in the cycle.
You can make up any number and it more likely to be wildly wrong on either the upside or downside.
Even comparing lithium companies with copper or IO or diversified miners is totally flawed.
The current boom/bust in lithium prices is a fall of 70%+ in prices. This doesn't happen often in other commodities, but when it does, then if you look at FMG from 2011-2015 boom/bust, the share price dropped by 75%.
Even BHP went from $40 to around $12. Nearly 70% down.
Then trying to apply some PE valuation comparing PLS to other mining companies in boom/bust, should the PLS share price not also be expected to fall close to 70%?

All I'm saying is you are making a wild guess, same as others here, and then believe that to be accurate and try to convince others that your valuation is accurate.
If they don't agree, then you get upset, and they get upset. It doesn't look good, both ways.

At the bottom of the cycle you should expect the shares to be cheap.

I think PLS slides lower from here. If I was applying boom/bust logic(you have to apply some logic, but some made up PE idea is less accurate in my thinking), then I'd say 70% drop from $5.60 to $1.68 + $0.70 cash after paying tax gives a bust bottom price of $2.38. Spodumene prices would have to stay low(below US$1000/t) for a while probably to get below $2.50. That is about where I would buy. What do I think PLS is worth at some point in the future? I would have no idea. Maybe double or 4x the low. I may take a gamble though and buy around $2.50 if it ever gets there. If it doesn't while lithium prices are still low, then too bad, I just won't buy.

Good luck with the guessing game. Everyone can have their own opinion. You may just be right.