Do many people who opt for long term get into very good iits? also please let me know the percentage of students (repeaters) who join iits every year

@ srestha 
No, there is nothing like that . the entering to iit depends upon the hardwork that u put in the two year , in 11^th and 12^th . 
the people are taking drop due to the following reason 
1- got good clg this year , want to improve next year 
2- attempted board this year , so, cannot cope with the pressure . 
3- got nothing this year , so, try again in next year , 
4- prepared this year without coaching , bt want to take coaching in next year . 
SO, OBVIOUSLY DROPPER WILL HAVE TO IMPROVE IN THE NEXT YEAR , BUT EVERYTIME THE CASE IS NOT THE SAME . 
EVERY YEAR NEARLY 40 PERCENT DROPPER STUDENT JOINS IIT , 
HOPE IT CLEAR YOUR DOUBT 

ALL THE BEST ..

Dear Student, its not true that many people opt for long term courses at IITs, actually a limited number of aspirants only do that, and to best of my knowledge there is no such a need to drop a year and to prepare for the test or to re-appear in the test when there are countless opportunities to seek admission at some other equally renowned institutions like IITs/NITs etc. I may recommend some names here which have earned a very good name and fame in this regard – College of Engineering, Pune,.......................SRM University, Chennai,.............BITS,Pilani,.................Lovely Professional University, Phagwara