2 questions alternate to pfitz 18 55, and Saturday tune up races

I'm planning on a spring full. I've successfully done pfitz 18 55 for two pr's, and 12 55. I like the plan, have not had issues with it, but in the quest to keep my training novel, and. Not increase the volume too much (55/60) is really as much as I have time, commitment, and recovery for at 45 with a family, job, and home life. Are there 18 or so week plans I can look at that have similar distance / intensity as the 18/55?

Also, if I do 18/55 again there are a number of tune up races which are always plotted for Saturdays.... Why? Almost no races are on Saturday. From a training plan perspective shouldn't they know this and design a plan with regular racing in mind? How do you all deal with these Saturday tune up races. In the past I've just done individual tt's with a target time on a known race course where it's more accurate that watch based 'gps' distance. This way I'm simulating the 6.3/13.3 that happens in real races and not the shortest distance that watch based tt's can do.