Why so long? Will they need to go through another round of FAA approval? Or?
For the second stage, my guess is they triggered the FTS due to the telemetry issues or just for safety's sake, i.e. they didn't want to take any risk with the lack of telemetry.
Most likely it was on board automatic FTS.
There is a trade off between data per flight, total timeline, and overall cost.
I dont think data per flight is the driving goal. There are lots of unknown, and if you stop completely for every problem, you are aren't learning about new problems.
As long as they get the ship up and make some progress, it isnt critical if these boosters blow up or sink the bottom of the ocean as planned
They have 4 boosters built and 3 more in production, and FAA license for 20 launches per year. My guess is that if the fix takes substantial time, they will work it into future production and keep going with what they have.
just look at Ariane 6...
Starship is a hardware rich program, the next version are there and nearly ready. Unless a major redesign is required (unlikely) it can happen much faster.
This is the old one: https://www.faa.gov/media/72816