the problem is that a "good scouting system" comes with, or rather means, buying lots of young unproven players for little money and giving them the playing time and patience for them to develop into the new star players of tomorrow ... some of them will turn into those star and repay that patience and investment ... for every single player who turns out to be a success, however, there are 10 others who will never become anything more than average ... it's more a question of trial and error and being able to do many trials before one turns out to be successful than any of the smaller clubs really having a superior scouting system to those of Milan, Juve, Inter, etc.
Mid-table teams can afford to this, in fact, their financial success and sole existence depends on it ... big clubs however, with all the big expectations and pressure to win NOW, cannot and have to rely on investing in already proven players, who of course cost a lot ... of course there is the occasional exception to the rule but that's usually how it goes
Depends, which players and what age.
Some players are born leaders and with quality, and they don't need much time to settle in. Let's not forget it's Manchester United who kept playing C.Ronaldo at the age of 18-19, Messi at Barcelona and Hamsik, Pastore at their current clubs. Those aren't weak teams but nonetheless, proven young players never take too much time to settle in and those players are well known. It's the style of thinking that keeps Italy backwards. Look at the management, coaches and even people from Italy, they an implemented mind-set of how their primary focus exactly is experience. Did you see the new bullshit recently? Some guy said how Pastore is too young for Serie A and it's exactly what happens literally and how clubs do think. Nobody will go after Kwadwo now, but every club will rush in to buy the mediocre Montolivo for the same amount of money, while Asamoah will go aboard and become three times better player. Nobody will go after Sakho, but for Bonucci and you know what's the reason? Well, Bonucci has the

Serie A experience
We skipped on Hamsik for 6mln euros but we signed the "proven" Almiron and Tiago, look what happened later. Almiron flopped badly while Tiago lurked every single penny from Juve's bank. Piqué was pretty normal but they kept on playing him and look what happened.
Everyone laughs at Sanchez. Maybe not now, but they did so many times. He was being called a trick pony, but it seems they keep their mouth shut now. He always had the potential and he's turning into amazing player. So what does proven means? That unproven Sanchez would make this Juve look different this year but most of the clubs prefer the "workhorse" such as Pepe who offers nothing literally, simply a good bench player. Unproven Hamsik was always better than Tiago, Almiron, Marchisio. Unproven Cavani was far more useful than Iaquinta.
Mourinho at Porto signed 13 players when they were third. Season after, half of those players were worth over 15mln euros and they ended up with a CL in their hands. All of those were inexperienced and unproven players. Now they are one of the best defenders Pepe, one of the best defenders at Chelsea - Carvalho, Deco who was amazing, Lisandro who banged in goals like there's no tomorrow, Bruno Alves and many more. Chelsea took a "risk" with Luiz and started playing him right away, he will become one of the best defenders.
Dortmund - Subotic, Hummels, Götze and Barrios have wiped the floor with experienced Bayern and they will win the title. Their transfers were written at a sum of 18.5mln while Bayern's was 118mln euros.
It's crystal clear that clubs in Italy are doing a weird job with the money they posses and it's clearly seen in Europe as they even lost the 4th CL spot.