This is possible in all leagues, not just Serie A. But from what I've seen here, some clubs don't have great stability, even in some matches they're unpredictable. But there was a change at the start of this season, where their inconsistency decreased a little and led to something good.
Not only this problem, but their internal problems are also still happening. Like for example what Juventus have experienced lately, although now they are better but still it gives a negative impression. I understand that there will always be problems within a club, but they should have anticipated them better.
Some people say that Inter is starting to be inconsistent or has started to show that its performance is declining, but for me that won't happen because Inter Milan is a very experienced club. In fact, all of these achievements are thanks to the support of Simone Inzaghi strategy as a coach who is also very experienced and in fact, right up to the match. Yesterday Inter was still able to get a win and maintain the top position.
Juventus is indeed a tough challenger for Inter because they continue to chase points with a small difference in points and on the one hand, Juventus has more freedom to continue to win because they only have a match schedule Series A, while Inter has to win the title 2 competitions and if Inter makes a mistake 1x looks like Juventus will take over first position.
I don't agree with you on this, even though Inter Milan is a very experienced club, but that doesn't guarantee they will completely avoid a decline in performance. Maybe in recent years they have shown something good, but if we look back, for example in the 2014/2015 or 2016/2017 seasons they also faced something difficult. Yes, it happened a long time ago, but it also cannot be denied that it will be their record that they can also still experience difficult situations.
Past records like that must be used as lessons for all clubs not just for Inter Milan.