Changing a failing car battery really in my opinion comes down to how important getting the car to start is.
If it does not matter overly that occasionally you have struggles then tolerating it might be tenable, but there comes a time where you are just putting off the inevitable.
I keep a CTEK 0.8 Amp unit plugged into our infrequently used tow car, via its tow socket, all the time when garaged.
I have found historically these techniques yield very acceptable battery lives. I also on both vehicles drive with the stop start off as I can't accept that this system does the battery or vehicle any good. Living in and largely using vehicles in a rural place where it if being active would only typically be instigating momentary stops, I suspect it also then does little if any good environmentally.