If its builder grade towards the lower end then I could see it. Our door frames are original at 56 years and look fine.
Thanks. I'd be careful with your plan, though. We tried to do the same thing with our deck, sanding down using a floor/drum sander, grinding the paint off between boards using an angle grinder, and patching in boards that needed to go. Took forever and was quite expensive. In the end it didn't look good, even after using a deck wash and brightener. It's almost impossible to get the old wood to look great, and it's completely impossible to get it to match the fresh stuff. After all that work we tore all the old boards out and put in new ones. It was a giant waste of time and money, but a great learning experience and quite a bit of good exercise.
Good luck! But if you have to patch any sections, please don't make the same mistake I did.