It really depends on what level swimmer you are.
If you’re a beginner, spend a 2+ weeks doing 100% drills. Stick with the balance drills at first (side kicking, shark fin).
As you progress, slowly decrease the amount of drill work you are doing, and replace it with longer swims and eventually interval work.
As an advanced level swimmer, I recommend still doing 10-15% of your workout as drills (usually as part of your warmup).