White vinegar works really well for cleaning that grimy scum off the shower door. It also removes white rings on floors and furniture where moisture has caused damage. You can buy a big jug of vinegar and use it full strength or dilute it. Plus it's way cheaper than scrubbing bubbles!
I would steer clear of anything that promises to clean your shower that is transmitted by air. Whatever is in the air is going to get into your lungs and body. When water droplets are present, this transmission happens even faster. You get a big enough hit of toxins when you shower anyway, due to the presence of chlorine and other chemicals in the water.
The reason I let the bleach sit for a day is that it breaks down in that length of time into water and salt. That way, it's not as poisonous when washed down the drain.