The finger sticking method is much preferred to a schedule, in my opinion Harriet. There are too many variables.Temperature (yes, even in your house), humidity and light levels dictate that one cool, dull rainy week you might water only once, but the next sunny, warm dry week you would need to water twice. House plants are subject to the weather, even though they are indoors especially in the spring and fall when you might have your windows open to the outdoors.
Different plants need different amounts of water, too. Some might thrive on watering every day but it would kill others.
Location in your home might also dictate that the same type of plant in a north or east facing window would need a lot less water than one in a west or south-facing window. Size and type of pot, age and health of the plant, all are variables that contribute to the 'right' amount of water and frequency of watering. A clay pot dries much faster than a plastic one, for example.
How about taking a roll of masking tape and a pen around with you when you water, write the date on a little piece of tape and stick it on the back side of the pot (or on a leaf?) to help you remember when you watered last? A simple list stuck on the fridge (or wherever you will see it) with notes about each plant for reference might help you to remember which plants to water more and which less.
