Waiting for those moments is unquestionably market timing. Nothing wrong with it, but you have no guarantees that they will recur, when, or by how much.
If 6% on a bank preferred is an acceptable yield for your investment purposes/objectives, there is no need to wait. In waiting, you may get your 7%-9%, or you may not. Further, you can always buy more should the price go lower, taking yield higher. However, what you can be assured of, is that you've locked in your 6% (or whatever based on what your first buy point is) and will not get any less.
I have a number of bank preferreds that I've been nibbling on, am happy with at this time, and will buy more should they trade lower. I also have one baby bond (exchange traded debt) that I've been nibbling on as well as it trades lower - it matures in November 2026 and has a 7% coupon. It was just issued November 2021. It's been knocked below par and now has a yield to maturity of 9.8% (for 4.5 years). If called November 2023, yield to call is 15.8%. This is not a junk issue either.
Anyhow, my point is that once the yield gets to a place where it meets what you're looking for, there is no necessity to wait for more/better. At the end of the day, we do not know where rates are going or what might happen along the way. The same way you look for black swan situations to take interest rates higher, we could just as easily have one where rates are immediately taken back to zero, or even negative.
Your objective is waiting for those events and making a quick profit trading on it. Nothing wrong with that. However, most other folks are looking to lock in the income stream.
Folks interested in preferreds or exchange traded debt should get familiar with quantumonline.com, as they have very good resources for searching and investigating these.