The answer to that very much depends on the piece, your personal preference and your technical skill.
If you have a large jump - say, from an a2 to an a3 - in a romantic violin concerto, within a very lyrical passage, you are likely to be able to take the time to shift on the e string. Even if you hear the shift quite clearly, it may fit with the music, and was possibly even intended by the composer.
Were you have such a shift in a fast orchestral passage, however, the situation would be entirely different. There, precise rhythm and intonation would take precedence, so you would try to get high up on the a-string beforehand. There is absolutely no use for shifting there, because if the whole orchestra performs a large shift there, rhythm, and a good part of intonation, will likely be gone.
As a rule of thumb, the faster, more technical and less soloistic the passage, the smaller the shifts you want to make. Of course, there are exceptions.
Additionally, you need to consider that fingerings can sometimes make a large difference in the color of your sound. So, ideally, you would want to play a phrase on the same string - obviously, that's just an ideal, which is why we practice string-crossings. But it's a thing to keep in mind.
Having said all that, and despite how nicely one can state all reasons when one should shift and why, you also need to be able to technically do it. If you are too unfamiliar with large shifts, don't do them. At least, in pieces you intend to perform. Practise them, though. That's one skill that's very useful to have on the violin. There's lots of exercises - off the top of my hat I'd recommend Sevcik op. 8 or Eberhardt's "Absolute accuracy of intonation on the violin" (awfully pretentious title, isn't it?). They are both fairly dry, and don't give much in terms of technical explanations, but the exercises are very healthy for one's technique. Also, in order to get used to high positions, just play passages high up. Eg fingering exercises you do regularly, just one string lower. Or two, if you're feeling brave.
Finally, I did interpret your question not as inquiry about how to do large shifts but about when to do them - I hope that is what you meant to ask.