I believe shoulder press is suppose to be before bench press . Better to have shoulders fresh and build those shoulders for this routine, I made huge progress with this routine running it the way it was written. Also you may have started to heavy if you started losing reps.
The biggest advantage to making this routine work is to walk into it, don't run. Give it a few weeks of gettin use to it before it becomes real work. You have to let your CNS get use to a full body before hitting it hard or you will wear out quick.
I ran this routine 2 different times for over 20 weeks each and it's truly one of the best routines for gettin in shape. Adding muscle while burning fat with this routine is not hard to do.