How often do you upgrade turntable ?

Same TT since 1987. Bang and Olufson Beogram 8002, now with a Soundsmith smmc1 cartridge. Still sounds good to me!

Got an LP60 and upgraded to a Uturn almost instantly. Kept that for about 2 years, and then moved up to a Mofi Ultradeck. Coming up on 7 years with that table, and just got a Hana ML so I suppose I’ll keep it for a few more years. 

I’m mostly drawn to belt drive tables, particularly from VPI and a few others. But I think my next table will be the 1200G, unless they make something more interesting before I move forward. As much as I’m drawn to the romance and upgrade options with other options, the near zero maintenance of the Technics will likely satisfy me longer term. 

After 14 years of using a mediocre Audio Technica LP120 with the stock cartridge, I upgraded to Rega P3 with an Exact 2 cartridge about 3 years ago. Considering, that I'm not DJing and listening for pleasure only, I'm extremely pleased with my current setup. If anything, I'd dip my toes into the MC arena first before upgrading the deck. I'm not one to cycle through upgrades - both because I don't have the disposable income or desire to churn through equipment but because I haven't felt the need to.

Maybe, I'll entertain an alternate setup like the Technics 1200 for swapping cartridges for fun once I get my listening library/den built in a few years.  But will keep the P3 as well. 

I upgraded my turntable about every 5 years starting out when I was young.  As my disposable income increased I upgraded.  Stopped upgrading when CDs came out and then I started upgrading CD players.  Now I mostly stream and have updated my DACs and streamers.  I find the time to upgrade has shortened as the technology in music listening has evolved.