During some casual searching, I typed in 'mumbai calicut'. A
couple of ads offered me tickets between the two cities.

I clicked on the first 3 ads. Jetlite and
Yatra took me through to their home pages. Where did
MakeMyTrip take me?

Which of
the sites would you book at?
Makemytrip saved me
the trouble of scrolling through two long lists of cities.
This, I'd guess, is the sort of thing that'd sway the
'marginal' traveler (say, someone who needs a ticket for the
next day. Or someone who's booking at 9pm, really wanting to
get back home.)
There is, of course, a cost
involved in doing this. You'll have to configure perhaps a
couple of hundred landing pages with pairs of cities that
you want to target. You can do this only if the increase in
conversions makes it worthwhile to take the effort of
customizing landing pages. And if you've enough transaction
volumes to recover your costs.
This is a great
example of customizing user experiences to suit visitors'
needs.