Have you tried putting moisture retaining gel crystals in the compost when planting.
Works well

Well I wouldn't recommend it - strawberries growing in the ground surrounded by black plastic is not the same thing as black plastic in pots. For one thing, you won't be able to see or feel the top of the compost to check on water requirements.

Fact is, when its hot and windy, smaller pots do need watering daily, sometimes twice a day if they're really small. The bigger the pot, the longer between waterings, but even large (12 inches wide by 18 inches deep) in full sun will need water every 4 days or so in such conditions.

Hi, welcome to GoY, plants grown in containers need a lot more attention to watering, than plants in the ground, so in a sunny position in a decent summer, you could end up watering twice a day, early morning, and again in the evening, I wouldn't recommend using plastic sheeting, because the soil would still dry out, from the heat on the side of the pot, or transversely could keep the compost too wet in a wet summer, Derek.

You can cut watering work a little by standing your pots on gravel trays and watering into the trays. You then have to be careful when it rains though as the pots should not be left for very long standing in water.

A good layer of mulch would help, well-rotted manure or gravel/small pebbles (dending on what you grow/the look you want to achieve)
Most of my 'garden' is in pots - last summer I watered them only when it hadn't rained for 4 successive days - I didn't have to water very often! My yard is enclosed though and doesn't get very much sun.

I have a big plastic bin near my pots. Save pure soap water from the bathroom in plastic containers. Carry downstairs to tip in the bin. When its very hot, drop the container plants into the bin every 2 days, guggle guggle, let them have a good soak through to the roots depth.
I have tried bark chippings but they tend to float away !

p.s. Forgot, large plant saucers are a good investment
as the watered plants keep some moisture underneath.
It soon dries up though.

Guggle guggle - I like it!

Thinking about Steragram's advice re gravel trays (part echoed by Diane) a variation on this is to use pot feet to lift your pot above the gravel and just level with the top of the tray.
Insert a fabric wick (a length of cleaning cloth, old towel etc) through the bottom of the pot so that it trails below the pot and can be buried under the gravel.

That way the pot won't get waterlogged by standing in water even after heavy rain (unless the whole area floods!) but there will be a reservoir of water in the gravel tray.