Whether or not a bowler should keep score in practice depends on the goals of the session. When working on developing your technique or adding a skill, the old advice of ignoring the scoreboard remains true. In fact, it’s best to not even have pins if the center has the capacity to do that.
On the other hand, when you are preparing for an event and want to mentally rehearse for the pressures of competition, or ensure that your lane play skills are sharp, keeping score is the only way to gauge your preparation.
Essentially, the more your practice focuses on the physical execution of a skill, the more you should avoid scoring. When your practice focuses on the application of your skills, then keeping score can be an effective method of evaluation.