If a ‘problem’ like that occurs, I simply introduce silence of 100-200 ms between the two clips. Nobody will hear it, and let’s face it: there are no 2 CD-players that will treat my placement the same way. With crossfades it’s a little more tricky - usually trial and error will do and on the other hand, there will always be part of clip 1 in clip 2 at the transition, so more is acceptable here.