ROI is important when you are starting, while you are still constructing new buildings. after that its much more important how much you make per building slot, and (this one is very important) how much a quality of research gives you.
I will elaborate it on the case of gas vs. wardrobes in r1:
One wardrobe gives you +60q, and you need 4 researched qualities to lift product quality by 1. So lets say for calculation purposes that every researched quality is worth 15 caps per wardrobe produced.
One gas gives you +1q, you need only 3 researched qualities to lift it, so its 0.33 caps per unit of gas.
now consider factory and joinery with same amount of workers, at same level, optimized. factory gas output is 14.5 times the output of joinery wardrobes output. one wardrobes research is therefore worth 15 x production of joinery, while gas research is worth only 0.33 x (production of joinery x 14.5) = 4.8 x output of joinery.
and another thing is, of course, finding decent buyers. I sell for example my wardrobes production for 3250+60q in r1, because i can make high quality and a huge amount, which results in me being able to price the wardrobes at 4750 for q25, which is probably more than many people sell their wardrobes in their stores for
(a bit of ego boosting here
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