Lots of people I know are too busy on their main project to even think of 20% time. It's nice to know that you have 2 months of 20% time booked but it's not feasible for most people to bank it and then use it later.
I'd say that unless your 20% project is a pet management project then the chances of you working on it 20% of your time is pretty small:(
Most of the people that I knew who had 20% projects, it was something like getting unit test coverage up for their main project. Mine was maintaining my previous project for years. Some people do have cool ones, but it wasn't common.
That level of old, but not HP. It was actually the first company to exist off of 100% software sales/licensing revenue. (Not hardware sales, with accompanying software, like IBM in those days.)
Does anyone know whether HP had anything like 20% time in its earlier days? I've never heard that they did, but now that you mention it it does seem like the kind of thing that HP might have done.
Old-school HP was so awesome it would have made Google look like a Communist labor camp. As long as you did what they paid you to do, your time basically was your own, along with a key to the company stockroom.
I remember reading that Woz used his time at HP to invent the first Apple computer. (Then HP decided that microcomputers were a silly waste of time so they gave Woz back the rights to it.)
I'm pretty sure the major factor is your project manager; some are very liberal with how their managees spend their time, others require 20% can only be used for approved projects and set the bar higher than one would hope.
