@MinnieTruck there isn’t a maximum. Sometimes LAs will issue numerous drafts delaying finalising for months on end. Sometimes they will only issue one.
After issuing the original draft and giving you time to make representations, there is no further requirement for the LA to issue another draft if they aren't going to make any amendments or the amendments made are a result of your representations. They could finalise without consulting you again.
If the LA is refuse to amend when you make representations on the draft, it can be wise to push the LA to finalise rather than get drawn into a prolonged back and forth with the LA where the LA still doesn’t amend to a satisfactory standard.
Although that doesn’t mean you shouldn’t check and cross reference the reports/evidence/EHCP, and it does not mean you shouldn’t highlight and explain what amendments are needed. Neither does it mean not still trying to work with the LA to settle the outstanding disputes or collating more evidence.
What it does mean is months and months aren’t wasted without any provision and without submitting an appeal. If the LA drags out finalising an initial EHCP, the provision in the draft does not legally have to be provided. It isn’t finalised. And often where LAs get involved in a protracted back and forth, an appeal is still needed. Going back and forth delays you submitting an appeal for the time going back and forth because you can’t submit an appeal without the right of appeal, which you get on finalisation. This could easily be 6 months or even over a year (18 months in one case I saw) and then you still have to wait for a hearing as normal.