The "problem" with one at a time is that you are putting levers against your painted frame tubes or attempting to clamp those same thin, round, painted tubes to a bench.

With the right tools (alignment table), anything is possible. When you are using ad hoc tools the risk of messing something up increases with every additional tool applied to the frame.


Some people are very natural mechanics - they have a good feel for the kind of force that needs to be applied and the potential for tools slipping and stress risers. Most people do not have that sort of sense for things and half the threads in the mechanic section demonstrates this.

Spreading the frame with a minimum of tools decreases the chance of crushed tubes, scuffed paint and applying too much force. It is a very gentle method, and the only downside is that it might require going back to a lever if it isn't opening symmetrically - which in both my and FBinNY's experience is actually rare.

It is the most conservative and safe approach.