Usually HR call is to make sure they can afford you, and make sure your resume aligns with job. if there is another Phone interview thats usually a screening to make sure you can actually do the job with someone who does or manages the job asking you the questions. The In person joints are usually to make sure you fit the culture and they actually "like you". Anything after that should be an offer/explaining the next steps.
But if you are having 3-4 ACTUAL interviews that are being held on different days that is too much.
I see what you are saying and the same day interviews with management and the other devs on the team were definitely about cultural fit, the only technical questions I got were from the Senior Dev in the second interview after HR screening