What is the context of needing a full fleet?
A few points.
- If you add another ship, the danger is that when being attacked it'll pull out the extra ship rather than the most optimum ship. A lot of players play with only 1 reinforcement on defence because of this reason.
- Do you need another ship? With the meta fleets, battles are over long before you need your final reinforcement.
- There aren't enough ships to go around. If you're in GAC or TW, there aren't enough ships for every capital ship. Adding an extra to Executor for the sake of completion isn't optimum.
- What actually is the best ship? Maybe the Shore/Death trooper one. It's Empire and gives TM.