[ansible]

In some sense, the Shuttle program was in continuous development. But to give you some idea of the work involved in even the later launches, consider this:

Instead of inspecting 24,000 tiles by hand, they developed a scanner to automate the process starting with STS-118:

https://www.nasa.gov/home/hqnews/2007/aug/HQ_07171_Shuttle_T...

They had hundreds of techs, working thousands of hours per launch to get each orbiter ready. SpaceX is expending a tiny, tiny fraction of that effort to get each stage-1 booster ready for re-flight. Part of that of course is that the booster is coming back at sub-orbital speeds.

So it is more fair to compare the F9 stage-1 to the pair of SRBs used for the Shuttle. But even then, there was a lot of effort just to get the SRBs ready for re-flight.