Questions & Answers about Mehr ist im Moment nicht nötig.
Why does mehr take the singular verb ist here instead of the plural sind?
When mehr is used as an indefinite pronoun meaning "a greater amount" in a general, abstract sense, it is treated as an uncountable singular noun. You would only use a plural verb if mehr explicitly referred to specific, countable plural items (for example, if talking about guests arriving, you could say Mehr sind gekommen).
Could I use the word notwendig instead of nötig in this sentence?
Yes, absolutely. Mehr ist im Moment nicht notwendig means exactly the same thing. While notwendig can sometimes sound slightly more formal or urgent, in everyday contexts like this one, nötig and notwendig are completely interchangeable ways to say "necessary".
Since this lesson focuses on expressing obligation and necessity with the Gerundivum, why isn't a structure with zu used here?
The Gerundivum (such as die zu erledigende Aufgabe) acts as an attributive adjective—it must describe a specific noun that needs an action performed on it. This sentence doesn't contain an action; it simply describes a general state of being using the predicate adjective nötig. If you wanted to express this lack of necessity regarding a specific action, you would use a standard infinitive clause rather than a Gerundivum: Es ist im Moment nicht nötig, mehr zu tun (It is not necessary to do more at the moment).