RE watering...I have 5 Landscape Bonsai... 2 Japanese Maple, one 26 Trees and one 9 Trees and 2 Shimpaku Juniper, One 12 Trees & one 7 Trees and one American Larch or Tamarac 19 Trees and then 10 other single Bonsai plantings, JM and Juniper....
I water every morning thru Late Spring, Summer, and early Fall,,, using a garden hose with variable Sprinkler head on Shower setting until the Top of Ground cover is soaked and showing water, finish off with a light spraying of the Foliage.
All my Bonsai have excellent Drainage, I also use an inexpensive $10.00 Moisture meter that I stick into the soil of each Bonsai every once in a while to be sure they are needing more water...
I've used extra care when Potting these Bonsai, keeping the Root system as intact as possible, squishing together the roots to a compact ball, so to speak....
My soil is a Pre-Mixed "Akadama Like" mixture bought from Flower Market in Dundee, MI, very little Potting soil only enough to give the Mix some Body.
When buying and potting various Bonsai I always keep all the Soil they are potted in & over the years have developed my own special mix with overall drainage in mind, VIP...
Spring, Summer, Fall I Fertilize once a month with Miracle Grow All Purpose 24-8-16 One tablespoon per 18oz of water.
All my Bonsai are very Healthy and growing Prolifically, I might back off the Fertz....
Not saying my way is the correct or only way....Just my way.
Hopefully this info will help anyone Not Sure about Watering and Growing their Bonsai...