I sell a lot of different spreads and I always use DELTA as the adjustment criteria. It is a more logical and common-sense approach than some random P/L number.
That's the beauty of options. There are dozens of strategies that can be employed by a trader. Outright purchases or sales of Puts and Calls, strangles, straddles, spreads, etc.
Likewise there are a many ways to enter those trades. E.g. using strikes that are ATM, ITM, OTM, same or different expiration weeks or months, using strikes that are close or far apart, using stop or limit orders, using the greeks (e.g. Delta), IV, probability, etc.
And, many ways to exit a position. Expiring OTM, stop orders, limit orders, using delta, using a defined P/L, etc.
I have a trading plan (written) and within that plan a trading strategy that, thus far, works for me. I use specific entry and exit techniques that, again, works for me. I don't pay a lot of attention to the greeks except for Delta and Theta and consider that criteria for my entries.
Trading credit spreads I know, going in, the maximum profit and maximum loss the position offers. I let the position expire OTM or I exit at a defined profit or defined loss, both numbers known before the trade takes place. I do consider Delta in setting up the spread trade (10 or less for the short strike), I do not consider delta when closing the trade.
I also consider IV and the potential for the price of an option to move a certain distance given the current price and with time left to expiration (as discussed in pages 78-80 of Natenberg's
Option Volatility and Pricing book (2nd Ed.)) Of course all that is computed for me on the ToS platform.
That works for me and has been profitable over the years. Your experience may be entirely different. As I said everyone's trading plan and trading strategies are different and what works for one person may not work for another.
However, I am always willing to learn new techniques that might be a consideration in future trading activities. If you want to provide an example of using Delta as the adjustment criteria for a credit spread, I and the other readers, would be most appreciative.
Best
