Square rule seems to me to have a couple of drawbacks. I feel like seeing if anyone else sees these problems, sees through these problems, and/ or what they think or might do about it. First there are only two types of square rule that I know of. You can use the edge of your timber to square rule or you can use chalk lines to square rule.

When using the edge you come across the problem of timbers not being straight enough.
A tie beam that holds joists or a plate that is bowed could be an example. If the tie beam that accepts joists has a bow in it and you use the edge square rule you will have joists that don't fit. A little persuasion with trucker straps can be helpful. It seems you can do a little of this with bent pre-building, but what about timbers in the wall planes thereafter, or vice versa. I guess because of this people started using chalkline square rule.

Chalkline square rule is good because all of the reference lines meet up and you do not have the previously mentioned problem. The problem you have know is faces that do not meet up that frankly look ugly. For an example: You have a king-post with a collar. The collar is bowed in the level plane, so you snap chalklines for reference. You lay-out the pre determined dimension for the mortise to accept the king post off of the chalkline. Then after it is assembled you look up on your collar and see the endgrain of the kingpost shoulder sitting proud of the collar. In my opinion, this is no good.

Wasn’t’ square rule developed so you could come up with set instructions such as 2” to 2”, ½” Under Nominal, etc. and people could work and assemble with expedience (I.E. no mapping of joints involved). But how do you get around these problems without resorting to scribe rule, or mill rule? Is the only way around this very thorough timber designation and liberal culling? It seems you would have to pick each timber in an entire frame and designate its specific place beforehand, and then by the time you got to cut it, it moved.

Thanks for any input, Mo