In theory that's true, but I was speaking to a guy about this the other day (who really knows his sh!t), and he said this is a common misconception: the difference in recruitment time can be measured in hundredths of a second. The fast twitch fibres are initially recruited in the very beginning of an explosive movement; the slow twitch fibres are recruited almost immediately afterwards.
I think I have some answers...
First of all, on the whole fiber type thing: different rep ranges generally doesn't recruit different fibers. The way the body recruits fibers is like a ladder. In other words, your body will always recruit the slow-twitch fibers first, and then add fast-twitch fibers on top of that as needed to complete the movement. But it's not so cut-and-dry. There aren't really clear divisions between slow- and fast-twitch, it's just like a continuum, ranging from very slow to very fast and a lot in between. And the body will usually use slow first and then add faster and faster as needed. ** The one exception is with really really fast movements. In that case the faster activation times of fast-twitch may cause them to be used almost exclusively.
So why is it that people who train low reps heavy weight do not have the stamina of someone who trains at the other end of the scale and vice versa?
People have noticed, as you have that the rep ranges someone chooses to train at affects strength and strength endurance. People often attribute this to differences in fiber type, but in actuality it comes from training the different muscle cell energy pathways. There are three possible sources of energy and they are ATP-CP (extreme short-term), glycolysis (medium term), and oxidative (long-term).
Which of those get used depends mostly on rep ranges as well as rest times between sets. Muscle ATP is greatly depleted after one set, but has 99% recovery in 3 minutes time. Powerlifters almost exclusively use this energy pathway, and as a result become quite efficient at it (also at neural factors relating to lots of maximal lifting).
From the bodybuilding perspective, rep ranges don't matter that much. What does matter is the number of total reps and the weight used. You can perform 30 reps at X weight as 3x10, 6x5, or whatever. People can and have built lots of muscle using anywhere from 1-20 reps. From strength perspectives, however, you want training to be sports-specific. If your sport is powerlifting, of course you should be doing low reps with a lot of rest. If you require more sustained strenght, up the reps and decrease the rest time. If you don't care, like I do, cycle the rep ranges so that you get a little bit of everything.