Shortcut to extend the duration of multiple frames at once?
While animating I often find an object moves either too slow or not fast enough, I have a feel for time and movement and can tell, if I extend these frames by a certain amount before I move the object again I can make the illusion more realistic. The problem is the only way I think there is to do this is by altering the duration of a frame by the needed amount by selecting it and pressing f5 to increase or f7 to decrease it's duration, as many times as I feel I need too.
Which is bad if you have a 3second shot (72frames) of something moving from one place to another an have to select each one of those frames and extend or shorten it's duration before moving onto the next one, it gets tedious. I thought maybe highlighting the effected frames and pressing f5 or shift/ctrl f5 would do this but it didn't. Is they a shortcut around this, or do I just have to extend or shorten a frame, one frame at a time.

