I do not leave it on. I use it primarily to reduce glare and reflection. Its another tool in my toolbox to be used in certain situations. An example; this past weekend, I was shooting a drag racing event (actually 2 if truth be told) with a lot of sun glare. I could put the polarizer on to reduce the glare from the sun reflecting off the cars. However, that would cause my shutter speeds to slow down for my chosen ISO and aperture (photographic triangle) which was unacceptable. Therefore, I did not put it on, but started shooting at different angles and positions to reduce the glare as much as possible. The sun chased me all day. On the other hand when shooting indoors in museums, I have used it to reduce the glare while shooting through glass to better see the exhibits. So it can be used outdoors and indoors depending on the situation. I hope this is helpful. Filters are just tools to be used when there is the need and will enhance your shots.