One thing on this board that has come up a few times, is the seeming 'sharing' of MI/Trek guest stars/day players, and this book has solved THAT question. Joe D'Agosta makes it very clear that, as he was casting director for THREE shows (he cast The Lucy Show also), he could work deals with actors for guaranteed appearances for a reduced rate - instead of someone getting $1,500 for one episode of Trek, D'Agosta could guarantee him/her a Trek AND a M:I at $1,000 each. That made everybody happy - a 'working actor' of the 60s getting 2G for two shows would be a pretty nice pay day in those times. Plus - two credits on prime time TV. And the studio saves itself a grand. 2 Grand was pretty good money back then - probably would pay someone's rent for a year!
So that's why you would see Malachi Throne, Windom. et al. in both shows.