If you miss the occasional tempo session should there be much of a problem? Since sprinting is focused more on power than anything, I would think that missing the occasional tempo session might not be that detrimental. On the other hand, missing a speed session would limit progress more would it not? Thoughts…
The answer to your question is of course “only if that session was the one you needed to improve”.
As Henk Krajenhoff told me we all know what we need to do to get results and that is “every workout you give the athlete the workout that they need”.
So if you needed that tempo workout to help regulate your nervous system or increase circulation then it will affect training in the long run. Similarly if you don’t stimulate your sympathetic CNS at the right time (with speed work) it will perform sub optimally and future workouts will suffer.
So you can’t say one is more important than the other. Everything is equally important and over time your ability to judege what is required and do the right workouts at the right time will ultimately decide how close to your maximum potential you are able to get.
Lovely Reply, TC! 
Your post is very well done and I agree that each training element is important, but I still believe that the high intensity work is more important. On one of the videos Charlie states that some coaches spend too much time on tempo. I guess he is probably referring to volume per session, but this leads me to believe that since sprinting is directly related to speed and power, high intensity work should have the priority.
Although it is optimal to have a tempo session for recovery in between speed sessions. Some people, such as myself, are forced to miss a day of training and I would conclude that missing a tempo session would have less of an impact on overall progress than missing a speed session.
If your programme is such that you are forced to miss a “formal” tempo session every now and then, I suppose it’s not a big deal, or you could perform some other elements you think you need to work at (e.g., flexibility). Or even try reducing your high-intensity sessions to two in times of heavy schedule; you might be pleasantly surprised!
Having said that, your speed, or high-intensity sessions will be as good in terms of quality and in the long run as your recovery methods; tempo is one such recovery method!
You can’t really separate them…
Yes, high intensity work is the priority- that’s why tempo IS important as a means of increasing the effectiveness of the HI sessions.
If you must miss tempo, some options:
Hot and cold therapy
Cals at home
swimming and or pool workout if available
EMS pulsing of the muscles
IMO, sprinting ie. speed work is FAR more important than tempo.
Yes, tempo is important but it is only a means of recovery for your real training - speed. You could definetly get faster by only performing speed workouts, but can we say the same thing about tempo?
Missing the occassional tempo session is no big deal - but missing it reguarly, whilst still performing speed workouts as if you were doing tempo, is bad and will run you into the ground.