Quoted from ForceFlow:Some guidelines on deadline extension requests:
https://www.lexisnexis.com/authorcenter/the-journal/b/pa/posts/seeking-time-extensions-in-litigation#:~:text=With%20some%20exceptions%2C%20Rule%206,extension%20and%20show%20excusable%20neglect.
I don't see anything about hard limits on the number of times a deadline can be pushed back.
However, if a judge feels someone is wasting the court's time, the hammer will probably come down on that behavior.
From a Constitutional perspective, there is, theoretically, no limit to the number of extensions potentially available in a civil action, like a bankruptcy. In contrast, criminal defendants have a Constitutional right to a speedy trial and an inordinate delay can jeopardize that fundamental right. Civil litigants have no such overarching right.