I think the question on whether to change can depend on the type of flying you do. If you regularly fly with anoher person or wish to take an additional passenger then the C172 or PA28 makes sense. Equally if the additional airspeed is meaningful it might be worthwhile.
I went from PA38 to PA28 - very straightforward. Then from a PA28 to an Icaraus C42 microlight, couple of hours but straightforward. I went back to the PA28 and that was curiously harder, getting back to a much heavier aircraft took a while, especially PFLs.
But, I think once you've flown a few different types and you've built up a reasonable number of hours, a check out on a different type becomes easier as you are more confident and better able to simply fly it by the numbers.