To add to what dondon said, I could also cite that Tellius gives BEXP if you go fast and that FE12 outright encourages hurrying up in the harder modes in clever ways.
EDIT: I am, however, a believer that FE is a game that can be played in a plethora of ways. Find out what you like and stick to that. Don't diss the other side for not liking the other and vice-versa. Having tried most ways to play FE (casual [sorry if this offends anyone but idk what to call it], LTC, "efficiency", maximum LTC, draft, etc) I like LTC and drafts the most. I do my first run of FEs in casual, but I rarely revisit that style of playing after the first run, doesn't mean I don't enjoy that first run though. I've just experienced the story, most of the supports and what the game has to offer so I don't feel the need to play like that again. I do, however, like to revisit the game to achieve lower numbers every time. :P