How many times can a B2 visa holder apply for an extension to stay?
Technically, there is no limit. The regulations simply say that B2 extensions of status are granted in 6-month increments. There is nothing in the law or regulations that says you cannot get 100 6-month extensions of B2 status in a row. Of course, the likelihood that the officer will find that you have a legitimate reason for an extension of status will decrease with each additional extension.