Your welcome, in my case almost always net debit . Say on call side I'd pay a premium for an otm call say at .75 (-.75) then sell a higher call strike for .50 (+.50) with net debit of -.25 each contract. Profit limited to the difference in strikes -.25, downside risk is limited to -.25
That's just an example of a vertical spread using same exp week. I'm sure you know that already, sorry.
It doesn't have to be a combo tho I've opened calls or puts long and then sold higher or lower strikes respectively against them later on in order to lock in profit and or lower overall capital at risk. Or have a planned spread trade and leg into both sides based on intraday chart.
Of course the profit is limited (to the difference in strikes + premium or net debit) but then the downside can be significantly reduced as well. It works for me since I usually sell early and the full difference in strikes or maximum profit. is prolly more than I'd sell for anyway.
You can go net credit as well and be protected or have maximum loss of difference between strikes.
Anyway, sorry to bore you, thats more of a swing trade strategy for me with spreads and combos. I sorta see what you mean about margin and risk for a day trade, i suppose the upside to selling/writing naked is taking advantage of time decay factor with it being close to exp.
All in all, I'm pretty sure you can open and close out a short put at any time tho (capital and margin requirements satisfied). Personally, I never did it before as stand alone and thought there was maybe some loop hole or an experience you had with that. European style options might be a whole different ball game and more accurate to what you stated.
FWIW, below is a decent tool in calculating any option combination positions. Take care
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