I know that the prepositional phrases "in/on the mornings", "in/on the afternoons" and "in/on the evenings" can be used as adverbials.
But I don't know whether the noun phrases "the mornings", "the afternoons" and "the evenings" can be used as adverbials too.
To find it out, I came up with the following sentences:
(1) The mornings it was raining, I went for a massage. The mornings it was sunny, I went to the beach. — I think it's correct but I'm not sure. So, is it correct?
(2) Mornings it was raining, I went for a massage. Mornings it was sunny, I went to the beach. — I think it's incorrect because these mornings are specified and, therefore, require "the" as in (1).
(3) In the mornings it was raining, I went for a massage. In the mornings it was sunny, I went to the beach. — I think it's correct and "in the mornings" means "during the mornings".
(4) On the mornings it was raining, I went for a massage. On the mornings it was sunny, I went to the beach. — I think it's correct and "on the mornings" means "on each of the mornings".