I have said it several times in guild chat. The research time appears to be from my experience this.
Research time = 6*2^(number of reasearches done).
So first research is 6*2^0 = 6*1 = 6h
2: 6*2^1 = 6*2 = 12h
3: 6*2^2 = 24h
4: 48h = 2days
5: 96h = 4days
6: 192h = 8days
7: 384h = 16days
and the last one 6*2^7 = 768h = 32days
Choosing the crafting passives can reduce the time, but imo, not that significantly really. If you could have 20% time reduce (is it 20% cant remember) right from the start, all you would save at the end of last research is total of 12days and 18hours. Well... it reduces the total time for researching one item type entirely from about two months to ~1.5months.
This all, ofc if my quick calculations and assumption on research times are correct.
So, if you keep playing and get the passives you should be getting in probably something like half year all of the researches. Personally I havent found any "must have" set locations anywhere. Best that I'm using myself requires only 4research to craft thus required time to get all items with set I want, is rather small. I dont find the research times to be problem....yet at least.