I'm really curious about the t-shirt project being a "micro-project". When I heard micro-project, I thought a couple of weekends of working, small niche market, and mostly electronic based. Teelaunch seems to require a large physical component (t-shirt printing and distribution). Even if you print on demand there's still a lot of work to be done there and high capital expenditure.
Somewhat lame question, but when somebody talks about their 'weekend project', do they mean:
1) A project I started and launched in a single weekend
2) A project that I worked in my free time (aka weekends)
3) Something else.
I've done some small side projects in my spare time, but have never been able to do something start to finish in a single weekend. Maybe my weekends are too busy or my projects too large.
By that I mean that I think people often mean both. Some projects are obviously hackathon-like projects that were done in (something close to) a single weekend.
Others probably took on the order of 4 days to a few weeks cobbled together over weekends. I worked on http://lifestyle.io/ for probably about 5 days total before launching it, and I've given it additional love since.
I wouldn't get hung up on what you can get done in a weekend anyway. Focus on creating real value with what you do if you're intending to profit. (Hint: many of these weekend projects forget that part entirely!) If you just want to have fun, then you definitely don't need to worry about timescales.
I feel getting the right kind of feedback, or the right kind of information is the trick. How much value do you get from the various quantitative approaches you took? What just felt like navel-gazing?