I think that you missed the part about 4 offsets all with the same spacing in between them. You would need to add X to each conduit to ensure that the equal spacing was maintained.
I like the benders where the 30 degree bend has the handle in the verticle position but not all benders are designed that way.
Oh sorry, missed that. I use the rule of thumb 1/4" X distance of separation. For 3/4 conduit, I subtract the starting point of the first bend by 3/4" to maintain a 3" spacing.