I think the folks at the link meant to say "assumptions," rather than "observations." Looking at the other items in the list, this seems to be the case.
In reality, radiun DOES matter. Otherwise, we'd all be pulling through LB's. Farther down the list, they do reference the need for sweeps.
Likewise, our own experience is somewhat different on the other points. We run oversize pipe when we can. We've all seen the limits of adding a pull string for future use.
Most notably absent is any reference to the friction of different wire insulation types.
Let's not overlook the difference between 'pulling tension' and 'sidewall pressure.' Since rather small wires are involved, the use of steel sweeps for the turns is indicated in a PVC run. While the poster is running steel pipe, that is not always the case.
(Too bad the original poster didn't use 2" rather than 1 1/2". Had he done so, he could have used his pet ferret to pull those three little wires for him!)
[This message has been edited by renosteinke (edited 12-19-2006).]