I also found that advice about as confusing as all the other consumer-targeted houseplant advice. If you've got some time to invest, then I believe you'll find that advice for professional growers makes a lot more sense, much more quantitative and backed by trials and chemical or biological mechanisms. I quite like:

https://www.fs.usda.gov/treesearch/pubs/46345

That's a guide to operating a nursery, developed by academics seeking to distill the scientific state of the art into something practically useful with basic equipment.

Specifically as to judging how much to water, I go mostly by weight. Thoroughly wet the medium until water runs from the holes in the pot, and then don't water again until the weight drops below some fraction (e.g., 20%) of that maximum. You can use a scale, or judge by hand with practice.

You can also wait until the plants show drought stress. For example, they might visibly wilt, or succulent leaves and herbaceous stems may go from turgid to limp. That's probably not optimal, but it's better than overwatering.

Finally, you can also pot in media with very low water holding capacity, like a blend of normal potting mix and perlite. This makes it near-impossible to overwater, but the tradeoff is that frequent (e.g., every few days) watering then becomes mandatory.