I tend to merely use a single retrofit step myself, mainly because of the reasons PvK had underlined (and because I am quite lazy as well). A single retrofit is usually enough to cut down the construction delay by one turn, and the vessel will then remain in orbit for repairs, which should be completed in one turn if you have a decent repair ability (82% with the Berserker culture). It is somewhat expensive, although nowhere as costly as the full retroseries way, but can be helpful if you do not have as many SYs as you should.
In the later game, the full retroseries way is probably much more appealing, when your basic income is a seven-figure number. *Coughs* Roanon's Collective. *Coughs* But when you are that wealthy, the galaxy will fall under your dominion no matter how you build your ships.
