I’m looking to hire someone to write a simple virtual device for me. I have plenty of programming experience, but don’t have time to learn groovy now. I have a light connected to a z-wave switch. This light can be white, blue, or white and blue. When turned on, the light is white. When turned on, off, and on, the light is blue, and when turned on, off, on, off, and on, the light is blue+white. The virtual device will have four settings blue, white, blue+white, and off. The z-wave feedback will only be on or off. It can’t know the color of light, so when selecting the light color, the app should turn the light off if it’s on and then go through the sequence above based on the color selected. Let me know if you’re interested and how much it will cost.
SmartSwitches don’t toggle reliably enough in a short period of time to do this, IMHO. You’ll never have a z wave device that will work reliably 100% of the time. It’s going to miss one of the 5 toggles at some point.
I had this working well with Homeseer HS2 Pro. It doesn’t have to be perfect. I mainly like to have the blue light come on at night, but there’s no way to do it without programming and if I’m going to do blue, I might as well do all 3.
That’s a fully local system.
A custom Virtual Device in SmartThings will only run in the cloud. That means roughly 500ms to 2500ms minimum between each on and off.
How quick do the “toggles” need to be? I’m guessing … 300ms to 800ms?
I implemented the most basic on/off pattern you want for one of my zwave switches. Let me tell you it’s unusable in ST. ‘not perfect’ is an understatement. You’re better of with setColor(math.random) on your light on button press 
I really put a lot of afford into it and it didn’t work. Main problems: timing in ST is hard and unreliable and as @tgauchat said cloud latency. Sometimes it even randomly skips or misses execution completely.
I ended up buying a new switch 
your better off to just have a regular smart bulb and get a cheap amazon echo and tell it what color you want
I’m trying to control a high end LED chandelier, so a regular smart bulb is not the answer. I appreciate and thank everyone for their input. I’m glad I didn’t waste my time trying to learn groovy to create an app that wouldn’t work. The light I’m trying to control also has an RF remote, so I just ordered a Broadlink RM Pro and will try to control it with this device. Hopefully, that Broadlink will also be better than the ZRTSI at controlling my Somfy blinds.
One remaining SmartThings option you have is to use an MCU (Arduino or similar like ESP8266) which is connected to SmartThings via WiFi.
The program on the MCU would receive the 3 commands, using line voltage relays, can easily issue the toggles reliably.
I appreciate everyone’s input. I gave up on Smartthings, returned the hub and all of the devices that I purchased for it, and purchased Homeseer HS3 Pro. They’re having a sale, which negates the cost difference. I was able to get everything working with HS3 Pro in a few hours versus the days I spent trying to get things to work with Smartthings.