As a follower, sometimes i find that doing our routine is easier to create the expression because I don't have to concentrate as hard on following compared to if we were doing freestyle. Plus, unless the lead is really clear, following freestyle ends up being a lot of guessing sometimes and it makes it hard to really go for it in the emotional department when I have to focus hard to do my job as a follower. For me at least ;-P
We compete with choreography. We're also in syllabus still so i think unless you really know all the syllabus rules about which figures can connect with which, a planned routine would be a lot easier haha. Even so, I think for pretty much all competitors, stuff happens on the floor and i do think quite often people have to deviate from routines due to floor craft, starting position, even different floor sizes. We've been to some comps where our foxtrot standard routine didn't even fit on the floor where it does on a 'normal' floor (even with trying to zig-zag deeper to make the long wall shorter).
I really appreciate all the responsibility that the lead has for this task. I think also, having a strong understanding of music will likely make a lead's life so much easier so it's not necessarily quite so hard thinking about trying to pick back up in the correct phrase (not just on the beat)..... this is what we're currently experiencing. I'm happy at least my partner feels the pulse of the music now, but re-starting off phrase after a slow foxtrot collision feels like riding in a wheelbarrow with a square wheel. We have some back up plans too... but I admit, sometimes i get a bit too involved in feeling the music (and what MY opinion of the musicality should be) that I can be a tough lady to lead when things go off course LOL