Workout at less than 100% or shift workout day?

[Doo]

There is a chapter in Cressey's Maximum Strength called "The Muscle Between Your Ears". I liked that chapter especially the section on "Low Motivation". I rarely skip a workout. If I do, it is because I do not have access to a gym but even then I have a set of IronWoody resistance bands that I make good use of.

What is more often the case is that I shift workout days. I tend to favor M/W/F for my 3-day-per-week routine. Cressey suggests that if you don't feel up to par (lack of sleep, a little "under the weather", etc.), to go ahead and work out at as scheduled at <100%. He believes that you could set yourself up for more execuses later.

However, what if you shift your workout to M/Th/Sa because you had to work an extra 4 hours on W and you think that you will have a better day on Th. This has worked for me quite often but I have ended up with the next day not being so good either and in that case I try to suck it up and do the best I can...for that day.

So, what do you guys think? Do you think that a flexible workout week with regards to actual days (maintaining at leat 48 hours rest between) is ok? Or, do you think that a backslide starts with shifting days and then progresses to missing days?