How often do you upgrade turntable ?

@huang - Not unless you want to! 

Still have a SYSTEMDEK IIX from the mid 1980's that I bought almost 20 years ago. 

Great sounding TT for very little money that has been quite durable, and does scale nicely with a better tone arm and phono cartridge. 

Like an oil change in the car, every 5,000 miles. ;^)

Sorry @inna, don't mean to make light of your question.  But it seems as long as one is satisfied with the performance and nothing breaks or wares out, why replace?

Yes, why replace ? Only to have something even better. Many keep their turntables for years, I suppose their speakers too. The rest usually gets upgraded more frequently.

"How often do you upgrade turntable ?"

I wouldn’t call buying 40yr old mint TT an “upgrade”! I have bunch of TTs, and  “timeless engineering marvels” regularly added to my collection.