Send out 2 messages that demonstrate your expertise or knowledge.
This could be about your business but it doesn't have to be. One of the people I'm connected to recently asked a question about how fog was formed . His 4 year old had been asking and he didn't know the answer. As it happened I did. (It was the only thing I learnt from my Geography lessons nearly 40 years ago). I tweeted the answer and he was pleased.
Was it worth it? Well we've since had some business dealings since then - so yes I guess it was.
Spend some time answering questions around your area of expertise.
If you use a programme such as TweetDeck (which is free) to write your tweets you can have an area that just shows tweets on a particular subject. I have a variety of ones which I change as necessary. I write a lot about job hunting so I have one on interview tips. Then I can see what people are asking about or commenting on interviews very easily.
You can do exactly the same for a product. As you see in the example below - I have chosen Kindle Cases a popular product for some WA members.
At any time you can change these topics. It literally takes about 10 seconds.
If people have a schedule of Tweet tasks daily as you have laid out, I definitely think they will be able to spend 20 minutes during their day and forget about it (other than responding to @mentions).
An automation training piece would be a nice follow-up to this, using a service like Tweet Deck. It can become a quick "weekly" task if this is done correctly. :) Thanks again.