I agree with booth of you, Henry and Brian...air tools in a time sensitive arena like flat rate or the boss on your butt asking if your done yet, will save lots of time. What I'm saying is that when time constraints aren't a concern and getting a car perfectly straight is the major objective, hand long boards and short blocks offer a precise alternative. This is not to say that you can't get a panel straight with air tools, you can...with the type of work I do now I don't do much work with respect to pulling large dents or laying filler over a complete box side...if it would come to that I would recommend the panel be replaced and a skim coat of whatever product be applied and hand blocked.
I waited many years to do the kind of work I enjoy and rarely do collision damage anymore (I still do the odd one for customers I've done restoration or custom work for in the past but nothing major). Brian...I have to admit, many years ago I saw an old man...back then I thought he was about 80 years old and I saw him doing the "old man shuffle" with an 8 inch sander in his hand...he attacked a Dodge Dart rear quarter (and we all know how flat those panels are)...All I saw was a cloud of filler dust and I swear to God, when he was done that rear quarter was as straight as an arrow. So, again, I have to agree that it can be done, I just prefer hand tools...that's my comfort zone.
And to the OP...sorry about the Hi-Jack...it might be interesting to start a thread about this topic.