Would it not be every afternoon ( like all afternoons) versus each afternoon if you translate literally?
Because 'tarde' means afternoon and evening, either should be accepted.
As far as I am aware, in Spain, which term used is not based on the clock, but different customs. Good morning is used until lunch has been eaten, even if this is 2pm. Good afternoon is said from lunchtime until it becomes dark. Good night is then used when darkness has fallen. So even if you meet somebody at 8pm, you would greet them with buena noches and say buenas noches when you leave them. Whereas, most probably an English speaker would say buenas tardes when 1st meeting and buenas noches on leaving them. I am unsure whether this custom is the same in all Spanish speaking countries. Helps when actually speaking to someone in the real world, but not in paper translations.