It's pretty bad to do that. I constantly find myself making outdated ships so they're all of the same class. If I make 10 Ship A, then 5 years later refit them to Ship A2 and decide I want to make 10 more Ship A2 I either have to make 10 Ship A, wait for them to construct, then refit them or I copy/save and make 10 Ship B. 5 more years later when I decide to refit Ship A2 to Ship A3 then refitting Ship A2 to A3 works, but Ship B now has to have a refit separately to Ship B2 so it matches Ship A3. More refits only make this more and more painful. It's to the point I'll rather continue making new ships of the original 20 year old design rather than make update base ships because I don't want 5 different class of the same design that I have to keep updating separately.
Can the designer UI be updated to show your cumulative probability of flaws in the ship designer? Even if you choose to leave out the base chance (60% IIRC) can it at least show what my techs reduce the chance by and what the cumulative +% chance is based on what I've put in? I can and do add it up to get an idea what my flaw chance is, but it's annoying to have to go back through and double check that the engine is 5%, the prop is 4%, the aux is 5%, the armour is 2.5%, the citadel is 10%, the reloading is 5%, etc. and add it all up on every ship because my designs don't always use the same components. Just a UI element that adds it all up for us would be nice so I can more easily see the flaw chance and balance it against the value of a component. And like I mentioned earlier it would be nice if the ship designer included the flaw reduction from research so if I forget to check before going into the designer I don't have to abandon the design, wait to load out of designer, check research and load back into designer again.
Not sure if it was mentioned yet but the ability to check the map or at least indicate where provinces are in the peace treaty concessions would be nice. I sometimes forget and mix up names on where locations are. Having to tab out to google a location to decide if I actually want to gamble on getting it is pretty annoying.