What is your horizon?? You must match it to the underlying.
(Look at their option chain from expiry to expiry: look for discontinuities.
If, by going from weekX to weekX+1, you are not getting at least your current portfolio-wide ROIC, consider looking elsewhere. (Or, at least *rank* them, and pick after other considerations.)
The IC underlying should be valued well above the differences between strike prices, so that you can best target the P(ITM) against the revenues received and margin consumed. (To answer another question: I prefer ES/SPX, as the $5 strikes allow for fair targeting on a $2300 underlying...)
FWIW, I aim for |0.20| deltas, top and bottom, on $5 widths, and/or >$1 total. I follow the SPX (and major constituents) closely, and may easily go |0.10| on one side, adn |0.30| on the other.
I put up both ICs and verticals, and work both until I am in where I want to be. Sometimes one gives me just what I want; sometimes I have to wrestle with the top, the bottom, or both. Despite being a bread&butter trade, I have yet to see a particular, lasting, pattern to that.
Two notes:
1) The volume on the monthlies (3rd week) is 5-8 times the volume of the weeklies, and THE BID-ASK SPREAD is ALSO 5-8 times the weeklies, for the risk of going Thursday close to Friday open with no viable exit.
2) If you enter with an intention to exit (e.g., sell 6 weeks out, buy-to-close 3 weeks out), make sure your owned strikes are in big, whole numbers that will sell easier. When the time comes, you can buy back your short with an order placed maybe 24 hours prior, but the sale of your far-OTM, single-strike, long position WILL LANGUISH if it's at 2205, for example, versus 2200. It's worth a little more risk, or a little less coin, to go to 2200.