It's less than 5% of my total investments too (I am young and don't have tons of money yet). I will check out that book, I've already got a good intuition for the greeks but don't know much theory on how to actually price them in if I were to sell options.

The thing I'd be worried about with medium term SPY calls is that you will be completely wiped out by a recession. Or even if a correction happened like in December and didn't rebound fast enough. Of course during a bull market that's a fine strategy (as long as theta/IV don't eat any potential profits) , and if you are socking away your gains it's probably fine. But if you are just growing your options allocation by 50% every couple weeks and then throwing it all back into the same position, eventually your double or nothing will come up nothing. Just something to consider