[Will]

Works great against AIs. But once a human opponent decides to take a pot-shot at that "impressive" fleet, and sees that a lot of them are only semi-built, they'll start bringing Long Range Scanners to see when there's a nice big juicy target for them to hit. You could compensate for this by placing a scanner jammer on each shell and warship, but then your opponents could also look for a large number of your repair-class ships to find a potentially easy target.

The main problem with the strategy though is cost. Once the shells are built, they start costing maintainence, and in vanilla SEIV, that equates to the cost of a new shell about every six turns IIRC. There's also the extra time and cost from retrofitting, and the 150% cost limitation, potentially causing the need for retro-series. Once you refit a ship, it starts costing the FULL maintainence for that design, while you might have to wait at least one turn for it to become active. It depends on your playstyle on whether this extra cost offsets the ability to have "bleeding-edge" tech on your fleets.

Generally, the better strategy is waypointing ships to a training planet (in vanilla, usually set up at a planet with two moons, to take advantage of three training facilities) to join a fleet, and go to the front from there, or to have a few construction centers with insane numbers of shipyards (depends on empire size, I've gone up to 100 BSYs against AIs before) in one spot, and either send the ships straight to the front lines, or train and send out.

The fortified WP over the Huge planet is one technique to bring large numbers of ships from one of the uber-yards to a front line. It usually cuts down a lot of the travel time for the mid-to-end game where warp openers/closers become common.