Is it bad to take glasses on and off?
Taking glasses on and off shouldn't be a problem if you function fine without them. Especially once you reach the reading glasses age of about 45, you will need different lenses for different distances. These may be different glasses, or they may be bifocals or progressives.
However, if you take off your glasses and squint to see when you should be wearing them will cause unnecessary eye strain.
Younger patients, especially those under 16, should follow eye care providers' advice. Prescriptions for them are usually designed to prevent or treat lazy eye, help with eye alignment, or prevent growing eyes from worsening.