I have just had to make a modification to SvnBridge because someone decided to checkin a change set that included 1,695 changes..
Even ignoring the issue of "your checkin broke my source control" mentality that I have now, this is bad from other perspective.
How do you review such a change? How do you even know what is going on there? In changes of this size, you aren't making a single change, you are making a lot of changes. Now you can't mix & match them either.
Prefer small checkins, they are easier to deal with.