From my understanding, TV schedules are a bit tighter than you're probably thinking they are. For example, the show Supernatural shoots on an 8 (week)day schedule - so 10-12 days per episode from start to finish (
Filming dates - Super-wiki).
Based on what the directors of the first and second episodes of the current season tweeted, Suits isn't widely off that mark. They started filming on Episode one April 7 according to the director's twitter.
The director for episode 2 arrived in Toronto on April 10 to do preparation and location scouting. They started filming April 18, and wrapped the episode on April 28.
Because you can always just film it again if someone forgets a line, the memorization and characterization part isn't nearly as intense as it would be for a staged presentation. For those, it's weeks of rehearsal at the pro-level (months at the community theatre level where I come from). And in interviews about the way they film, the cast has talked about how they'll do each scene a couple of different ways and then they get to improvise the scene once or twice (and sometimes that gets used).
Because film/tv is so dependent on what happens in the editing room, the whole question of consistent "must rehearse to do the lines a certain way" isn't as much of a thing in film production, from everything I've been given to understand (I have friends who work in television production in the GTA both in front of and behind the camera as well as the editing room).