There is the key
You "heard"
Many have done it in less time and less tries.
Every time a company brings on a new type they must do proving runs, evacs and ditching's
So Delta,United, American all had to do them (while public) when they brought on the 75,77, and 787 etc.
Southwest had to do one when they brought on the 73-800 since there was an added flight attendant
Imagine what the stockholders at the major's would do if it took 8 tries?
Oh but I forgot I don't know anything.