I add these to my numerous baskets and find I water each day but not twice in the hottest weather.

I've used them a lot too and found that I could water baskets in moderate sun about 3 times a week, those in shade normally twice a week, sometimes less. (We don't get extreme summer temperatures being near the sea.)

Those gel crystals are absolute magic - and you can use them in the garden for improving dry soils too. The trick is to get the gel at the bottom of the containers where the roots are, not sitting on the surface looking weird.

Really the best rule about watering is to do it when its needed. Get accustomed to the weight of the basket and you will soon be able to tell when it feels lighter and needs watering. So much depends on the site of the basket and whether it has been rained on. Also pay close attention to the look of the leaves - when watering is overdue they get a sort of dullish sad look. After a few weeks you'll get the idea of how often water is needed. Its as well to check every day though. Those gel crystals are marvellous!