The reason behind this for me is with working a Mon-Fri job the opportunity for a week to go a bit haywire always exists. Therefore planning from Sat onwards gives me a chance to have two days were I have a level of control over the outcome which is greater than during my work week.
Also it gives a opportunity to plan based on the gaps that developed during the last week in terms of impacts based on other commitments and responsibilities.
Also for me it gives a me a couple days to build confidence with training and consistency which is a mental thing I struggle with during weeks where I have a slow start training.
The other benefit I find for me is being able to adapt the biggest days of training (normally) based on my fatigue going into the weekend.
The last 5 days for me was pretty hectic so training was bike commuting ad a couple swims. Need to get better at jamming a runnin the crappy mid weeks so that is the lesson learned.
So this weekend on Saturday it was weights in the am (took the little one to the Richmond Oval) and hitting the trainer and treadmill tonight. Tommorow will look to run long in the am - have a easy spin in the afternoon and get a swim in at night.
That gets my week off to a solid start an hopefully take that momentum through the work week.