Now as to why Aamir movies get solo release of late is because of their quality. Its almost a forgone conclusion that his movies are at the very least good if not fantastic.
And that is what puts people off of releasing their movies on the same date. Its common business sense. With others there is hope that WOM can carry it over the other big release and the movie will do good business.
A reason as to why you are seeing clashes with BM, DW and also Sultan and Raees.
The day BW people can actually make a good enough movie to rival that which Aamir is in, you will see a clash. Baring D3; for the last 10 years or so his movies have always been in top 3-4 of the year. Now that's consistency.
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