I've recently read articles about working out your back in each workout, but separating the horizontal from vertical pulling exercises. I was curious with 6 day workouts or 6 day upper lower body workouts if 6 days of back exercises would be somewhat overkill.
There isn't that much difference between horizontal and vertical pulling movements. Horizontal pulling will require more work from the scapular adductors (trapezius and rhomboids) and less from the latissimus dorsi, while vertical pulling is the opposite, but there's still huge overlap between the two. So I wouldn't consider them distinct in the way that upper vs lower body, or push vs pull exercises are distinct.
Whether or not 6 days per week of back training is overkill depends on how much total weekly volume you're doing, and how much you're accustomed to. Alternating two sets of rows with two sets of pull-ups would not be any more fatiguing than doing a single back day per week in which you do six sets of rows and six sets of pull-ups. However if you're accustomed to doing six sets of each per week and then you decide to change that to six sets per workout, six days per week, that would be an issue in terms of both absolute volume and a sudden increase in volume.
Alternating horizontal and vertical pulling exercises 6 days per week would be a perfectly reasonably way of programming back exercises in the context of a six-day full body program, alongside which you'd probably do something like one of squatting or hip-hinging, and one of horizontal or vertical pushing each workout.
Common science suggests that 24 hours should be enough rest for s muscle.
Some scientific studies suggest that more than 12 hard sets per muscle per DAY can be overkill for the average individual.
Conventional wisdom suggests that you can train your body to recover faster and handle more work, also diet seems to help.
Everything I said comes from the website called strongerbyscience.