I aim to redeem my Marriott points for 0.9-1.0 cents, and generally can get it, but the caveat is that for every 10-20 trips I book, maybe 1 ends up being on Marriott points. In other cases I end up using other points (such as Hilton) or booking a cash rate, often at a non-chain property (usually through hotels.com or AirBnb).
It feels like a major hassle to keep checking whether Marriott redemptions make sense - because most of the time they don't. I don't tend to stay in high end hotels, so not interested in $500-1000/night stays. There are the occasional cat 2/3 properties in the US that make sense, but it certainly takes a lot of effort to get a true 0.9+ cents redemption. By true I mean, compared to a cash price you would realistically pay for a stay in a given area, not compared to whatever overpriced rates the specific Marriott hotel is charging.