I'm enjoying this thread.  Its interesting to hear various do's and don'ts, different styles and approaches to portaging.

One thing I've noticed as I've become more experienced (everything's relative...) is how much more quickly my paddling partner and I develop some sort of a routine (same guy takes same item(s) each portage).  The one exception is the canoe.  We switch off taking the canoe each portage.

I've become indifferent to portages.  By far my favorite part is the empty-handed stroll through the woods on the return leg of a double portage. 

Anyway here's my 2 cents (some of which has already been said):

1. developing some sort of a routine is good thing.  More efficient and less likely to leave stuff.
2. Loose items are a bad thing.  Extra energy and/or more trips.
3. No reason to rush. Too many bad things can happen when you're in a hurry (forgotten item, injury, etc).
4. Before I depart on a canoe trip, I pick a luxury item or two (for me its a comfy camp chair), but otherwise I try to give serious thought to the items that are brought along.  Is it really worth the weight?  No doubt this makes portages more enjoyable.