in reference to your question about the crusaders, they have won the super 14 more than any other team in the competition, they house international players such as dan carter and richie mccaw and the strength and conditioning coach is ashley jones who you can ask specific questions on this site.
i assume the reason for 5 continuous days is because it is set out for professionals and because of this its like a full working week but you could spread out the programme to suit your bodies own rest needs. the reason for so many vertical pressing movements/sets is because it is far more specific for rugby than horizontal pressing, most movements e.g. lineout lifting, hand offs etc are all done verticallr or on the feet. i personally when trying out this workout changed one of the shoulder pressing movements to a standing one arm barbell push (which can be used with or without the getstrength commando equipment – take a look at the equipment for a video on the movement i talking about). https://www.getstrength.com/training/GS-Commando
I believe the amount of sets is fine due to the difference in rep ranging from 3-8, for rest time between sets i used 60 seconds between the sets involving 6-8 reps but between 2 minutes and 2 minutes 30 seconds for the 3 reps.
just a few of my personal opinions on this programme but i used it for the latter part of my off-season training and saw great increases in size and strength with the only adjustment being that one movement.