don't be so modest.

720p is an acceptable low bar

For me, 480p is not even modest, it's close to the height I get for a landscape video when holding my phone in portrait.

I also don't usually need the extra pixels, as there is seldom important content in the fine details — a few years ago, when I was prepping to leave the UK but not everything lined up to the same dates, I was using PAYG mobile for home internet and therefore set the videos to 240p; the only reason that didn't really work was that not all videos had such low resolution, and when they didn't the site defaulted to 720p.

yea, 480p is ok for phones.

720p brings a noticeable improvement for watching on something 40"+ (tv).

going further to 1080p is only a marginal improvement over 720p so i usually "keep it simple/small"