Practice for most other sports rarely follows those guidelines. Professional golfers rarely practice by simply playing rounds of golf. They stay sharp by spending hours on the putting green, short game area, bunkers, etc. Honing their physical game and gaining feel.
A baseball team doesn't stay sharp by playing full games. has batting practice; hitting to specific fields, bunting, etc. Fielding practice where you would practice one particular throw or play over and over until it's second nature. Practice situations and that may not come up during the routine game. Pitchers have side sessions to gain better control and consistency.
A pool player would hit a particular shot hundreds of times until the angle, stroke and English would be second nature.
Bowling has an amazing drill, something anyone can do to work on dozens of faucets in your game and hone them into something so consistent, you won't even have to focus on it.... The One Step Drill.
There's really so much going on for a bowler to take a full approach and expect to focus on one thing, especially if it's something at the foul line. To earmark a tiny sliver, a micro second and expect you'll feel a consistent difference can be frustrating. Even if you do, the likelihood that your instincts will pick up this subtle change can be remote.
The idea behind the One Step Drill is just that. Done about 4 feet from the foul line, it's swinging the ball, allowing it to reach the top of your back-swing and THEN, take your final slide step as the ball comes down. This is not a full speed technique since you aren't taking all your steps and for that reason, you'll find lots of time to focus your attention on any number of checkpoints.
Perhaps your issue is seeing your target. Perfect! Swing the ball and focus your eyes on your target. 20 to 30 shots. Use your plastic spare ball and focus on an arrow. Maintain a level chin and eyes on your target. Swing and roll the ball keeping your finishing position balanced. Watch your ball roll through your target. If it's a miss, was it left or right? Again.... and again. Over and over until it becomes easy. Eventually it will.
Maybe your issue is a flying elbow and a tight grip. Maybe your pulling the ball down and not giving your fingers a chance to lift property. Fantastic. 4 feet from the foul line, swing the ball and let it freely fall to the bottom. Loose thumb and pay attention to your fingers. Let the ball roll off your finger tips. Elbow in and forearm face up. We aren't scoring. It's a technique we are trying to master. Change the mechanics of what our body is doing. Do 20 or 30 shots and eventually you'll relax that hand and it will become more obedient.
Now on to the blends; that's when you do the a couple one step drills and then do a full shot frame. This will give you an opportunity to monitor your progress by taking 3 or 4 more steps before you enter that the One Step Drill part of the approach. See if your body has caught onto what you're asking it to do.
15 minutes of drills; 15 minutes of blends, now time for a game. Try to score. Note the project and judge if a percentage of shots are affected. If so, that's success! The probability is that your game will be in a mid state, where you'll do a percentage of shots well and some not as good. Keep at the drill. Session after session. Change takes time but the alternative of polishing your game by simply bowling lots of full approach shots won't necessarily make you a better bowler.
In my life, it's done thousands of these drills. Granted it was in a different age where consistency was paramount. These days, you can get pretty far being smart with the pieces in your hand, the placement of your feet and chosen target. For those who want to climb the mountain high, practice drills like the One Step are a great way to change.