Here's a trick to get two consecutive or overlapping buffs from on-use trinkets.
Instructions:
1) Use on-use trinket before you enter combat.
2) Use alter-time.
3) Switch trinkets, enter combat, burst away.
This is probably an exploit but I couldn't really be bothered to debate the issue with whoever
says "Not an exploit blah blah blah" so I'm posting it here instead: