Quite often these lazer cut pieces lock together very nicely, and as such are glued in place. I've found that a rounded fuselage can be put together easier and more accurate if assembled and glued off the table. Just be sure to build over the plans so that bulkheads, etc. are located properly. Sometimes a wing will require a "washout" former to be pinned to the plans (and table) to give the ribs their proper angle prior to glueing.

Roger