I've been thinking about using Improved Scorch together with the Glyph of Improved Scorch in an efficient manner.
The macro I came up with is this:

Code:
 /castsequence reset=target Scorch, nil
/castsequence reset=6 Scorch, A, B, C, D
Note: reset=6 depends on the cooldowns of A/B/C/D and should be changed accordingly.

The first cast sequence makes sure that when you initially attack a target, Scorch gets cast. Then the castsequence gets to "nil" and gets ignored until we change target. Improved Scorch now gives us 3x2% crit, so we get 6% crit chance.
The next cast will then come from the second castsequence. Another Scorch is cast and another 6% crit chance is applied. We now have 10% crit, because that is the maximum. Then casts A, B, C and D are cast and the second cast sequence is repeated and keeps the crit chance active by repeating Scorch every sequence.

The benefit is that this works well in short fights(single target), since we use short casts(Scorch) and that it gives extra crit chance rapidly. It also works fine in longer fights, because Improved Scorch remains active by repeating Scorch once in the cast sequence.
The only negative side is that each time you switch to another target and back again, 2 additional Scorches are cast.