Agreed. Practice, practice, practice.
I'll share a story in my Collegiate days.
Back at that time (early-mid 90s), we at Univ. of Nebraska had our practice time on Monday evenings. We worked on everything (a given for collegiates); however, one of the things our coaches had us do was before we could head home for the night, we all started at one end of the house, and on each lane, we had to take the 7 pin and the 10 pin *only off the rack. If you took more than that off, you stayed on that lane until you took just those two pins off. If you did it, you went to the next lane and did the same thing.
Keep in mind, most of us had classes the following day, but it went late into the night for some, where it took an hour or longer to go through the alley. The first person done on either men's or women's teams finished in 45 minutes. Also, keep in mind that we really weren't using plastic balls for spares back then either.. most of it was either pearl urethane, or flattening the wrist.
This drill and one other alternate technique I may do led me to picking up so many 6-7s and 6-7-10s, I wouldn't believe it. On the other side of that ledger, you'd think it would be impossible to miss a 6-pin to the right with keeping the ball on the lane, but I've done that, too.
BL.