I think maybe what's worth a watch on the coming episodes will be shown as promos.
Yesterday even I noticed that most of the promos were for Drashti but maybe today we will get to see some other promos showcasing other contestants like Shweta.They have many promos a week and they aren't mad to give all the promos to Drashti.
I don't think Colors TV is partial in JDJ .The Madhubala thing is a way of promotion of the show I agree even I noticed that with Siddharth,Prats and now Drashti it isn't a new thing that what Colors does so why the entire blame on Drashti and to add a point maybe the judges saw her show and if you noticed even Karan Johar told that he saw Siddharth in BV and he is doing a nice job.
Drashti and Salman don't need promotion and even many stars on the show are popular names who don't need to be promoted as there are legendary actresses like Shweta,Aarti so it isn't the promotion here but what the viewers will get to watch in JDJ or may be Drashti's performance was the best so they are showing it or may be as predicted they got a perfect 30 this week.
But new names like Ekta should be given more promos