We teach that the imperfect designates an action normally occurring in the past that is continuous in nature. “Jesus walked by the sea” is aorist; “Jesus was walking by the sea” is imperfect.
And we also teach that there are different kinds of imperfects. “Descriptive” is the catchall. “Ingressive” focuses attention on the beginning of the action. “Iterative” is repeated action. “Customary” leaves a sense of time behind. But in all these, the action is continuous, ongoing.