I spend a lot of time doing drill #2. I like drill #2
When you spend this much time doing a simple drill little things pop out at you, like why is #2 so different from #3?
I have always done drill #2 as a trail wrist flexion (straightening) excercise. However you who do it will have noticed that there is a littl trail elbow bend that come with the wrist extension (bending back) to get to 6/100s. I took some time to do drill #2 as a mini-piston drill with no conscious flexion of my trail wrist. I am confident about my hand staying on plane (no pronation) so I felt this was a safe experiment for me.
As a result I think there is a value in drill #2 done this way. There is an added emphasis on the direction of the piston and on the precision in setting the club height in order to get consistent contact (it harder than drill #2 as a wrist flexion drill). This is closer to what you will be doing in drill #3 and on so lets call it drill #2.5.