There are probably good reasons to "skip" around when you are hand
soldering. For one thing, you can get everything flat on the board by
soldering one pin and then checking. For another, you avoid disturbing
the solder joint on say a resistor, by soldering all the south (or
whatever) sides first, then going back and finishing up.
I'm not so sure about the heat thing as you have to consider the ∗whole∗
board going through a wave soldering machine. I don't think a reasonably
competent guy with a soldering iron can manage that level of thermic
abuse!
___________________
John Blacet
Blacet Research
http://www.blacet.com