I am a new player, and as result I don't have proper routine yet, I need to analyse what was sold, what are current changes on markets I am trying to work on, decide on pricing and further experiments.
With my WoW setup I had about 40 positions I worked with on regular basis, and it took about 2-3 minutes to check current situation for all off them, decide what I want to do and about 2 more minutes to post 1-10 items in each position. I don't see how I can do it with SWTOR interface, I have to check each position individually, not to mention posting. With experience on each market it becomes faster, but now working on about 20 positions plus trying to watch about 10 more takes 25-30 minutes.
Sending companions is the fastest part and really less time consuming than crafting in WoW.
Pretty much your 20 min/day does not include time you spend on market analysis/experiments. With your experience you are not doing it daily, but it is huge time investment, and this is area where WoW addons were very helpful.