I think it's pretty individual. I'm currently reading 30 year old medical books on Psychoneuroimmunology (PNI) by Jay A. Goldstein. I've been comparing it to cu

I think it's pretty individual. I'm currently reading 30 year old medical books on Psychoneuroimmunology (PNI) by Jay A. Goldstein. I've been comparing it to current long covid research to get an idea on where progress has and hasn't been made. It has been enlightening to see how much of what is considered new today was known back then.