You will not get any benefit from using more or less buckets. The reason Couchbase has buckets is because it can be multi-user. The best use case I can use to use multiple buckets is a hosting provider, and you want different users to use the same database server. Buckets can be password protected and will prevent one user from accessing other user data.
Some people create several buckets for organizational purposes. Perhaps you are using two different applications and you want the data to be separate or, as you said, perhaps you want to separate the data into categories.
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