It should bubble after several hits damage are not
I will weigh in with this after reading everything.
If you cant beat a base OR dmg it enough for a bubble by hitting it 5 times or under, your junker or outclassed so you simply need to move on lol
If you can hit/destroy or hurt a base in less than 5 his then this wont affect your game.
Like in BP, the most annoying thing i have seen is some bottom feeder under my base, hitting me x times in a row just to stall me out for 5mins an attack, this serves nothing but time wasting.
Before reset i tested prepping bases, and thy arent easily prepped tbh. I think 1 storage few res gens and 1 turret bubbles, but killing 3 res gens doesnt bubble. I think the dmg per bubble may be alot more restricting than BP. But i hold to what i said above, if you cant beat a base by attacking it 5 times in 1 hour, then you shouldnt be allowed to restrict/stall the defenders game for an indefinite time. Yes you have a small chance of snaking the attacking fleet, if its only one, or calling for help from others so you can play your game seems restrictive.