That's assuming you ever need 7-night stays. I have never yet needed one ever. Once I needed a 6-night stay, and a few times a 5-night stay (mostly in places with no Marriott, like Igauzu Falls). Everything else has been 4 days or shorter.

So is it still a good value if you have to "throw away" a night or two or three, because of the 7-day requirement???

Even if I'm flying into someplace for 2 weeks, I'm never staying in one location for that whole time. I'm always out and about, exploring. The one time I did a 6-night stay, that was an airport hotel in the Madrid area, chosen because near the freeways and I was daytripping in a different direction each day. Same thing with 5 nights at a suburban Budapest hotel for my visit to Hungary (once I was done seeing the city proper on an even shorter in-city stay). But there's very few places in the world where the very same location would make the most sense for 7 nights/6 days of daytripping. (And how likely that these few places have a Marriott property, and that's it's a good value compared to the alternatives? Because, btw, I rarely tend to stay at top-tier properties. But does a Travel Package that's 7 days at a Residence Inn make sense???