Some people are cautious and use only one block in each part. This is not taking advantage of the power of TrueGrid® to build parts consisting of many blocks, most of which are connected. This is a great simplification because one does not have to spend much time getting the interface between parts to match.
Because there is this great savings in effort when building a part with many blocks, some people try to build a model with just one part. This too can be impractical.
You will get best results when you build parts with as many blocks as you feel conformable building. Then use the bb command to force the unconnected faces of blocks to match.
In case you may think that the bb command is equivalent to merging, you should know that it is not the same. The bb command moves the slave side of the interface to match the coordinates of the master side. They are still distinct nodes on both sides of the interface.
You must be in the merge phase in order to merge nodes. If you issue another merge command (such as the stp command) in the merge phase, you cause the previous merging to be undone before the new merge is executed. So merging before the model is completed usually does not help. I will frequently go to the merge phase while the model is only partially completed to check if I have build the parts so that they merge. There are numerous ways to check the places where the parts merged or did not merge. In other words I am checking my work at different stages of the construction. So there is a good reason to merge at different stages, but not for the reason that you stated.
