Our '23 Tundra Limited acts the same way; partly because I have a very relaxed grip on the wheel; but on a straight, smooth, and well marked road I have had "lane-centering-assist" go close to a mile in a true hands-off test. I believe I have it figured out; the following is from my own empirical testing. When in "lane-centering" mode the hands-free sensor tests for rotational resistance. In those long straight stretches it is not adjusting the wheel direction nor turning the steering wheel, so the rotational resistance is not tested. On curvy or uneven roads it tests and adjusts almost continuously, so it needs to feel that rotational resistance from your fingers.If you are considering "Drowsy Driver Alerts", please, please include a way to adjust the sensitivity or to selectively turn it off! Our Jeep Cherokee has this feature where it alerts via chime and an on-dash error telling the driver to place hands on steering wheel, even though our hands are on the steering wheel and we aren't drowsy. It seems to happen more when it's cold or when you are on a very long stretch of straight road. We figured out that it's tied to lane assist and if we turn off lane assist that annoying place hands on steering wheel alert stops. Jeep did not include any way to change the sensitivity or turn that feature off without also turning off lane assist.
I also find "lane-centering-assist" is very sensitive to lighting conditions. Low angle sun in forested areas which makes zebra shadows across the road confuses it completely. In places where long cracks in the road surface are filled with tar, it will sometimes choose to follow them rather than the painted stripe, etc. It will follow lines that are so worn I can barely see them, but add a few pothole patches to clear lines and it gives up. It works absolutely best in the pitch black middle of the night. Now that I have figured it out I call it a useful and friendly assistant, but un-trustworthy. I can live happily with it or without it.