The Osprey series? Seriously? A series of figure painting guides masquerading as history books? The series that featured a
radio direction finding loop on an American Civil War cotton-clad river ram? That Osprey series?
Sure, whatever.
You realise they have different authors right? The Fornovo and Condotierre books are excellent.
When you're able, find some actual histories of the period. Marcotti's classic biography of Hawkwood, for example, has been recently re-released. As you note, Mercenaries and their Master is also a fine book on the subject, but I'm surprised to read that you believe Mallet holds a good opinion of the condottieri.
From the Introduction "Mallet took a cautiously revisionist approach arguing that the gap between Italian practice and elsewhere was more illusionary than real"
The book tends to focus on the structure of the armies rather than the individual Condottieri. It paints a picture of a fairly advanced system that while it had poor leaders and bad leaders was structurally fairly advanced and prompted ideas that filtered down into France and other countries.
I've read a fair number of Italian history books but these are the ones I actually keep at home btw and I do not have a good memory for book titles.
When you're busily paying mercenaries it's hard to save money.
All states had problems paying for troops, they also had few standing troops. As other countries grew the tradition and amount of troops they could afford grew. Because Italy was a mess of states they lagged behind. There was also the ever delightful wild card of the Papacy who by turns invited people in, told them to bugger off and generally caused more problems than they solved thanks to the whims of the Popes
Odd considering how the warring city-states were all fortified. Then again, maybe someone didn't want all those petty wars to end, someone who was making money off the situation...
Taking any city is always difficult, it requires money and time, money the city-states would rather spend on the Condottiere actually doing something. The habit of encouraging them to despoil the country and live of the loot as part of payment also encouraged a fluid warfare rather than static offence.
There were sieges though, Pisa in 1406 the siege lasted 8 months for example.
Again, when someone else is doing all your fighting it's hard to keep up with any advances.
The Condottieri were often fighting abroad, they didnt exist in a vacuum, commanders often served abroad like Sigismondo Malatesta or Pippo Spano (Greece/Hungary respectively) as did contingents of troops, Genoese crossbowmen were renowned. Speaking of Genoa both they and Venice spent an awful lot of time empire building.
The decline of the condottieri system began in 1494 when Charles VIII's invasion showed the Italian states and their preferred military system could no longer defend the peninsular. For the next sixty years, foreign armies, most of which also included mercenaries, slapped around the locals with ease no matter whether they were allied with the invaders or not.
Not disputing this at all, but the weakness was not the Condottieri fault, not entirely. A quick look at Italian history will show a country where as soon as any bugger tried to set himself or his family up in power a dozen conspiracies formed to keep him in check, so of course this meant most people could only rely on family, which made people more suspicious and so and and so on until the entire peninsula is one big argument (and still is)