Water in a plant saucer: leave it or pour it out?
A little water in the saucer after watering is normal. For most houseplants, though, it is best to empty the excess after 10–15 minutes.

The simple rule after watering
Water until a little runs out through the drainage hole. Wait 10–15 minutes, then empty what remains in the saucer. That gives the potting mix time to absorb water without leaving the bottom of the pot soaking for hours.
Water thoroughly
Water should pass through the potting mix and leave through the drainage hole.
Wait briefly
You do not need to time it to the second; the goal is simply not to leave water sitting for hours.
Empty the excess
Lift the pot or carefully tip the saucer and pour away the remaining water.

After a short wait, empty the excess water.
Why roots should not sit in water
Roots need air as well as water. When the bottom of a pot remains submerged, the air spaces in the potting mix stay full of water and oxygen becomes less available. Over time this raises the risk of yellow leaves, sour-smelling soil and root rot.
Check the decorative pot too
Excess water often hides in a decorative cover pot rather than in a visible saucer. Take out the inner pot after watering, pour away the water at the bottom, and return it only when it has stopped dripping.

Water in a cover pot is easy to miss until you lift out the inner pot.
Are there exceptions?
Some bog plants and moisture-loving species prefer consistently damper soil. Even then, damp soil is not the same as a universal rule that roots should always stand in water. If you are unsure, check the needs of your specific plant.
Track watering, not just the date
Record watering, add a photo and use a reminder as a prompt to check the plant—not as an automatic order to water.
Open mygreen.world