You really need to qualify what you are measuring and that varies between who you read or listen to as well as your materials.
I also find a target density range of ~1.20 (Zone VIII @ 1.30 - Zone I @ 0.10) generally good for my silverprint enlarging materials but I hesitate to recommend that specific figure because YMMV. I've arrived at that figure by testing and by defining what I'm actually measuring (i.e., Zone VIII-Zone I). Others may be quoting figures derived from a different set of measurements and/or materials. Film type, developers with different curve characteristics, paper, enlarger type, enlarging lens contrast, etc., are all going to influence the results.
I think you will be better off just to measure the density range of the paper you are using and then adjust your film exposure and development to that rather than using someone else's target density range value. As you can see by the first few replies in this thread, the numbers recommended are going to vary. However, that doesn't mean anyone is giving you wrong information, just relating different experiences.
Joe