@[member="Circe Savan"]
For starters, he was asking a question, not making a point. Thus the question mark.
But to address the points all the same... The Empire is massive, yes, but not much larger than the Republic and about 2 to 2.5 times larger than the Mandalorian territories. Larger does not always mean better though, just look at Israel. Also, being large means you have a lot of strategic points that require defending and have a huge boarder that needs to be defended. So... Everything would not simply be parked at the capital.
Also, while the Empire likely has dozens or hundreds of individual shipyards, they would be consolidated at a few key worlds such as Dac. Unless you've specified that your capital planet is also your primary shipyard, it's unlikely that 'Spare ships' and prototypes would be laying around. That, and you'd want to be developing your prototypes in secret locations where prying eyes and civilians are kept far away.
That being said, I would expect a defensive fleet of 3-5 small-medium sized ships to defend important worlds in the Empire. And more so when it comes to defending the Capital. However... Would you really have anticipated anyone would be dumb/ballsy enough to charge through your outlining systems and make a strike directly on your capital planet? Realistically, the military/government would have trusted the planetary shield and network of defensive cannons to keep the capital relatively safe and would keep a minimal fleet of ships nearby 'just in case'. While the rest of the fleets are split up into battle groups and strike teams and sent to patrol Sith space. That, and as I'm aware of it, you've sent your 'flagships' off to deal with defending against a Republic push and sent a fleet(or two) deep into Republic space. Both of these Naval assets would drain you of resources and you'd be focused on watching your boarders during the conflict.
Who would anticipate a second attack? Let alone from one you just tried to broker peace with...
@[member="Kaine Zambrano"]
All in all, I'd expect 3-10 frigate/cruiser sized ships and some orbital defenses.