This exercise will help you gain control over repeating the same delivery time and time again. Just imagine how good you will feel in a game when you have four bowls all grouped together around the jack.
Without using a jack approach the mat and calmly deliver your first bowl. Watch the bowl as it comes to rest and then pick up and deliver your second bowl with the same line and action as your first. Repeat for bowls three and four.
The aim is to group all four bowls within a target zone. The size of the target zone will depend on your current skill level and can be adjusted over time once you are constantly getting three or four bowls together in the zone. To start with have a target area of two or three mat lengths, then reduce when you are getting scores of 3 or 4 on every end.