How often do I need to do a visa run while on a METV in Thailand for 6 months?

Karen , I will take care of it , don’t worry

you need to get those visas as close to when you're comin' to thailand as you can. They have a validity of 6 months from the date their issued so do that so you're not burning up the validity NOT being here ;)

Most people who do that get almost 9 months in country (in 60 day increments).

Once you get here you will be stamped in for 60 days, when that 60 days is running out you have two choices,

go to the immigration office and pay 1900baht to get a 30 day extension

OR

go to the border, stamp out of thailand, stamp in&out of another country and stamp right back into thailand to get a new 60 day admitted until stamp.

You do that for the entire length of your visa. If you exit/re-enter the country just prior to the "enter before" date on the visa itself you will get one final 60 day stamp.