Grappling week and striking week? Or one at a time.

Met a guy at my gym the other day who trains 3x/week-like me- but he alternates between striking week and grappling week. More specifically 1 week Muay Thai and 1 week BJJ. I have been focusing only on Muay Thai for this year and was going to focus on BJJ next year, but I’m wondering if I should try the alternating approach.

Has anyone tried this ?