You may want to take a look at post #70 by BelleBelle in this thread
https://forums.azbilliards.com/threads/a-word-about-learning-sidespin.523643/page-4
While that thread concerns sidespin, what he's saying applies to speed and just about all aspects of pool. If you like (speed) drills then
drill away but MPO is that time spent elsewhere will reap more benefits, including better speed control.
Every shot you play requires a blend of stroke speed, direction, angle, tip placement, elevation, etc. Many times there's a great deal of
subtlety involved and it's really not something you can put numbers to or control very well by conscious thought process.
Be aware of and put an emphasis on stroke development. All else being equal, consistency and quality of stroke will yield the biggest
and quickest results.
Why? It has to do with muscle memory. Let's say you're doing a drill and your stroke is poor. Even though you're trying hard, one shot
your tip placement is 1/8" aboveleft of your intended spot, the next is aboveright and a third is 3/16" straight below. You might say
wow, that's an awful lot but that's typical of low level amateurs. Then let's add in varying degrees of smoothness or jerkiness.
Every time you strike the CB under these conditions it yields a different result. That info is sent to your brain and over time muscle
memory is developed. The problem is that muscle memory doesn't know the difference between a wanted or an unwanted result.
For long periods of time confusion can reign and slow down the process. Conflicting results are not conducive to quick muscle memory
development.
On the other hand if the stroke is more consistent then more correct signals are conveyed. Speeding up MM is the quickest path to
improvement. It's involved in every aspect of a shot (including speed).
I've been a little simplistic about this. There's more involved. You need to constantly increase your knowledge and expand your
comfort zone. Every little bit you feed your brain helps.
If you're really serious about the game get Mark Wilsons book.