Sometimes. There's usually a lot of movement when lines first come out, and then a good amount in the late afternoon before a game. If you think the line will move higher and you like the favorite, you have to bet at open, which then pushes the line higher in a self fulfilling prophecy. When the line begins to move, anyone who wants the other side will wait until it stops moving to get the best possible line in the other direction. And then once it starts moving back, the people on the underdog side need to rush to get in before the number gets worse, once again becoming a self fulfilling prophecy of pressure downwards. And at some point, if there was enough movement, some people that got early lines on the first side may try to middle/gain arbitrage by betting the other side also, locking in a no-lose other than vig with upside to win both.
