There are 2 parts to tube wear & tear
Starting a tube requires "striking an arc" across a cold tube. These are, after all, in the arc-discharge light family. This will cause a modest amount of wear, or spallation, of material off the electrodes. (which you can see as a darkening band across one end of the tube).
This is helped by using "pre-heating electrodes" in the ends of the tubes - these will glow orange before the tube strikes.
Any non-broken fixture will provide tens of thousands of starts.
- An Instant-start ballast, which slams the tube with extremely high voltage at the cost of more spallation of electrode material, will provide 10-15,000 starts from a tube.
- A Rapid-start ballast uses the "pre-heaters" for 1 second before striking the arc. You can see the momentary delay after you throw the switch, and an orange glow on the ends of the tubes before the light strikes. These will give 15,000 to 25,000 starts from a tube.
- A Programmed-Start ballast uses feedback data to run the pre-heaters as long as is needed. They start with a momentary delay, but that delay becomes longer in the cold. These will give up to 50,000 starts from a tube. This is so good that people use them on motion sensors.
Run time is less of a factor than starts. But we certainly don't expect 10,000 days from a fluorescent tube, do we? That means shutting off the tubes at least at night is a win for tube life.
To say nothing of the electricity in question!
Anyway, it's really a judgment call. For something like a bathroom, where the lights will be on and off constantly, you either want a programmed-start ballast, or you might think about leaving the tubes on during the day.
Think about tube wear versus ease of replacing.