if you look at any other TR base plans you will see lots of work between .75 and 1.0 IF. there’s a huge discussion about the benefits of “sweet spot” training vs a more “polarised” approach. if you want to read more on that route I would recommend checking out the extensive threads Polarized Training Discussion (Fast Talk podcast & Flo Cycling podcast) - #11 by Bonne and Polarized Training Workouts & Experiences (80/20) - #10 by sryke
concerning the value of pioneer and the progression workouts (.8 IF for 45-105min), @Scheherazade has brought some good points forward. consider that the overall workload in a tri plan is quite high and fatigue management is important. with these workouts you can do relatively a lot of work in terms of TSS/hours, while not carrying too much fatigue to your other sessions. I found the HIM MV base workouts left me fresher with the rest of my plan than LV SSB2/SBP workouts.
(I also find the Pioneer etc. workouts to be quite challenging more on the mental than the physical side, but you adapt quickly)
NB there are many people here that do triathlon off SSB and SPB combinations, so it may be the right fit for some!