The three most consistent clubs in Spanish La Liga in the last two decades Real Madrid, Barcelona and Atletico Madrid like you rightly said did all had a busy summer. The three clubs made significant signings but I'm more concerned of how well these signings will perform for their various clubs when the new season kicks off.
Real Madrid who added Kylian Mbappe and Brazilian youngster Endrick to their team I think doesn't have much to worry about how well the players can perform in their first season because they already have a great team who conquered Europe and Spain last season and are still managed by Carlo Ancelotti who managed them last season as well. But for Barcelona, they now have a new manager in Hansi Flick who intends to succeed with his own style of football. Atletico on the other hand allowed some of their key players of last season to exit the club while they sign their replacement do you think the new arrivals will easily settle in their new clubs?
Regarding the new players recruited by Madrid and ATM, we may not need to worry. But what we should pay attention to is other teams like Barcelona. Now let's just look at the teams you mentioned, only Barcelona can't transfer players with better talent quality and all of that is due to the very bad financial situation. Madrid we can see Mbappe but in Barcelona we can't rely on anyone except the remaining players. And on the one hand the change of coach like Hansi Flick gives a higher impression of concern. Maybe everyone still believes in the new players recruited by Barcelona as long as Xavi still remains as the team's coach.