The caption on the thumbnail is "I don't drill for BJJ
anymore." So I'm guessing he drilled at one point.
My opinion is that you should learn the techniques in as clinical an environment as possible, and then once you know the techniques, work on them in dirtier ways.
For striking, it's a 3-phase process:
- Drill the technique without a target
- Apply the technique on pads, and practice against an opponent in non-contact or light-contact drills
- Apply the technique in sparring
For grappling, it's more of a 2-phase process, because there aren't pads for grappling and you generally need something to hold onto in order to "get it"
- Drill the technique against a non-resisting* opponent
- Apply the technique in sparring
*By "non-resisting", I mean they aren't just going with whatever you're doing, but they're not fighting you either. The purpose here is to learn how to do the technique correctly, which means you must have control (they aren't just falling because you grabbed their arm), but also that it is a cleaner environment. Part of this is that in a real situation, your opponent won't know what your plan is, while in a drill your opponent can actively stop you from doing what you need to do.
If you skip applying the technique in sparring (in either striking or grappling) then you won't learn how to time it, but you have to start with drills in order to become proficient enough in the technique to spar with it.
That's just my opinion, anyway, but every class I've taken follows this philosophy.