Showers usually use less energy than baths, but it all depends, doesn’t it?. Do you take shallow baths? Are you one of those people whose main joy in life is standing in a cascade of hot water until the tank runs out? If you shower in the tub, put the plug in before you take a shower of average length (for you). Now you know how it compares.
Nowadays a shower or bath per day is considered de rigeur hygeine. It wasn’t always so. Throughout the ages and all over the world, attitudes towards washing the human body varied greatly. Some of our ancestors stank to high heavens because bathing was considered unhealthy. The ancient Greeks and Romans were much more civilized with their great public bathhouses. In other times and parts of the world, baths were great luxuries enjoyed by only the wealthy. The less affluent took one once a month. It was a big deal to heat all that water and pour it into the tub. First the man of the house took his lordly time, and then the children got to take their turn, using the same water. Last came the wife to bathe in the dirty water. This might be where the word dregs comes from.
I think we have a lot of leeway to consider how often we want to shower or take a bath. A five or ten minute shower each day? A fifteen minute shower twice a week? It depends on your activity level. Or how often you go out in public!