Maybe here's a better way to describe the problem. As Italy, everything you build is far from the front, so you really need to plan in advance, and mobilization is often the most important decision you make. I'll lay out some disorganized notes off the top of my head - sorry, but it's the best I can do at the moment.
Imagine that Austria dies and is partitioned. Austria naturally influences five centers early: 3 home, Greece, Serbia. What's the likely result of this attack? Let's play it forward.
- Italy will get Trieste in 1901. plus Tunis.
- Turkey will slide to Greece, might or might not get it in 1901, but with no resistance to sending a fleet to the Aegean, is likely to get it eventually.
- Turkey will build a fleet to sent to the Aegean, either because it already has Greece and wants to protect it or because it will let Turkey force Greece.
- Russia will be in Rum/Gal/War with armies.
- Russia will *not* build F Sev, but rather armies to jump on Austria.
From here, what next? If you ordered Ven S Tri, then your new army is built in Rome, so where does it go? Your ability to keep Tri is blocking your ability to get anything else. If you ordered Ven - Tyr, you might have lost Tri.
So, Russia is likely to get Bud, Turkey is likely to get Gre, and Russia will want Vie while Turkey will want Ser. If both those things happen, then the end result of collapsing Austria has been that your neighbors got 2 builds and were given a strong incentive not to fight each other, while you got 1 build and two strong neighbors.
So, if you're going to attack Austria, you *must* have a plan to get either Vie or Ser, or else it's a bad decision. [In the long run, what you'll tend to find is that the power who ends up with Budapest a year or two after Austrian collapse is the ultimate winner from it.] Let's look at what's involved in both cases:
To get Vie: You need to outfight Russia. Russia will easily be in Bud/Gal, so you need 3 units (Tri, Tyr, Boh). That leaves a max of 2 other units. If it's two fleets, then you can't protect Trieste while you shift. If it's fleet/army, you're a wide open target for a Turkey who has noplace else to expand. Heck, if it's 2 fleets, a 3-fleet Turkey takes the Ionian anyway, so you're racing Turkey to see if you can take Vie before it takes ION. Try that race and you'll see you usually lose, though it's not certain.
To get Ser: The best you can do is Alb/Tri, while Turkey may well be in Gre/Bul after 1901. If Turkey is in both, it takes Serbia and you never get it back. If not, you'll either need help to get it or you'll have to cut Gre, so you're basically fighting a war with Turkey over Serbia and asking Russia to pick a side.
Oh, right. And if Austria ends up dying, and has a choice of which of his neighbors to screw over on the way out, guess who he picks.
In other words, your best-case scenario is that you end up in the 2nd best position of the three people partitioning Austria, and being 3rd best of the three and the next course on the menu is most likely. And we haven't even started to talk about France...
Italy is the toughest country to play in gunboat in my opinion; Austria has worse results, but when Austria goes bad in gunboat, there's rarely anything you could have done about it, so it's not that tough to play in such a case.
With that said, I think there are two key principles here:
1) As an Austrian neighbor, if you can get 3 centers, kill it; if you can get 2 centers, decide based upon your read of the board, but if you're likely to get only 1, Austria is your close friend and ally.
2) The most profitable way to kill Austria (or any neighbor) is usually to be the second power into the war, not the first.