Replacing sand in filter??

Hi, Recently I was talking with an acquaintance who also has an inground pool. She was telling me she had to replace the sand in her filter because it was 5 years old. Apparently the look on my face made her think I thought she was bat-**it crazy. She told me that "all the pool experts" she talked to said she should do this. I asked who these experts were and she named all the local pool stores. In the next breath, she told me she's stopped going to several of them because they were "not reliable".
Okay, confession time. I replaced the sand in my filter about 20 yrs ago before I joined this forum. Since then, about twice a year if the filter seems to be not doing much, I run some DE through. (I still have the same box I bought back then) I haven't had any issues in that time.
I guess this is a long way of saying thanks to all the folks on this forum who have probably forgotten more about pools than I will ever know.