A few years back I spun 4 oz on spindles, taking it everywhere with me, in about a month. That was for a spinde challenge, so I was fairly persistent about always having it with me, as it was fairly finely spun, too -- about 18 wpi 2-ply.
This last summer I spun 4 oz and 3-plied it into a worsted weight, all on spindles, in about 2-3 weeks of evening spinning -- I get an hour each evening to sit and do something quietly, so it's mostly spinning! That, too, was focused -- my mother was coming for a visit and it was to be a gift to her. Turned out great! (the yarn and the visit)