I check at least once a week. It may vary depending on location. We have a LOT of immigrants.
If you live near an upscale area, check their thrift stores.
It might be worth the drive. Usually there are several stores in an area. Check all of them out. Some are better than others. Goodwill is a complete rip off, you might as well buy at Walmart etc. Salvation Army used to be really good but not so much anymore. Try Hospice thrift stores if you have any nearby. Lots of really good things in most of them.
Your best bet might be church thrift stores. We have held our line on prices because we dont pay rent(because it is on church property) and we only have 2 paid positions so the costs to operate are very low.
Also if you are retired, think about volunteering at one. That way you can see how things work. How many donations per week etc. Every thrift store is looking for volunteers. We have guys that like to fix things, one older gentleman just comes in to sweep the floors, and a woman that just folds bags for us. There are so many jobs across the board at most places.