In the long run, getting chain reactions are worth doing that. If you are getting close to IV ending, I could see cutting out the frostbolts, but keep in mind that (especially with the new 2pc) frostbolts are key to gaining more BF procs (which lead to IV extension)
But if I do that, I should always be at 20+ yards right? Before that it's a waste to FB?
Also, hypothetical situation...
You just finish casting FB, and you have brain freeze and one FoF. Is the correct thing to do, dump the 1 FoF, cast FB, BF, IL?