I just looked up "at (the) most" in "Longman Dictionary of Contemporary English". It was under the entry for "most" as determiner and/or pronoun. One of the example sentences for it in the dictionary is:
It’ll take 20 minutes at the most.
But I feel its role is like an adverb. For example in the above sentence it seems that it adds more information to the verb, exactly the function of adverbs. Am I right?
Any response would be appreciated.