Number of boards taking interview varies as per availability and other responsibility. For example you can see there are e-summon for various exams are pending. So, they would be dividing boards for different exams. Hence, the number of interviews on each days is varying. It is normal.
Secondly, there is absolutely no correlation between interview date and mains marks.Please for god sake don't lose your sleep over these issues. Thirdly, on each day aspirants from different parts of our country are called for interview as per their roll numbers(which is based on their prelims centre).This has been happening for past 3 year
Hence, peacefully prepare for interviews without thinking over such trivial issues.
