Hi, I think a better master ship system would be to allow a ship to mastered if:

1) All parts are researched
2) Highest tier parts are bought
3) At least "x" amount of battles on ship
4) Or "x" amount of time spent playing ship


Currently, having to master the previous ships and also whatever extra branches the current ship leads into results in wasted time having to play ships you wouldn't otherwise want to play.