So it seems that many people say that you should water your average house plant once a week or so, or whenever the top 1 inch of the soil is dry. My problem is that a lot of my plants are on a window sill and receive sunlight nearly all day long and the soil in the pot dries out after 2 or so days. Should I water the plants weekly or whenever the soil is dry?
In my opinion, plants need water when they need water. Not on some arbitrary schedule. If the soil is getting dry quickly water them.
One thing you can do to help retain moisture is to use a layer top dressing, small gravel on the top of the soil. This helps retain water and it looks nice. Again, in my opinion.