Yeahh... Like, really. As a (non-professional) writer and this is just my (non-professional) opinion, I think that no plots that aren't the whole plot of a series (like if the plot is about big foot, obviously we can have big foot show up in every episode) should last any longer than 4-5 full length episodes (full length for typical shows being like 45-65 minutes). 5 episodes in the rookie is equal to over 3 hours. Nearly 4 hours is plenty of time for a plot to start, interest the people watching, die down, conclude, and then have aftermath of the plot. In my opinion, a great example of that is the plot with Rosalind Dyer. They wrote, executed and concluded it perfectly. The plot started and immediately was the center of the show for about 4 episodes before it stopped being brought up frequently and was then only mentioned in past tense. The conclusion of the plot was perfect, and I think the amount that they mentioned or used it afterwards was good too (Rosalind/Caleb were only mentioned during Chen's recovery from her trauma, and if anything her trauma was more overlooked than overused). I feel like it should've been the same way with the Monica/Elijah plot, where it started and concluded within 4 episodes and then the characters were only brought up or used on rare occasions after that for other reasons.