Either way, it seems to work the same for the LEDs.
I often see people online attach a resistor to each individual LED when connected to the Arduino.
since I only have a few 1k resistors.
instead of talking like that.
please explain to me why I am wrong
Either way, it seems to work the same for the LEDs. Is there any problem with the common-ground solution I have found?
Lower brightness is kind of a good thing for me--my LEDs are blinding!
If I understand you correctly, you are putting several LEDs in parallel and connecting them in series with only one resistor. If you can live with the LEDs being of unequal brightness this is perfectly OK. There is a reliability exposure if a significant fraction of the LEDs stop conducting (burn out) in which case the remaining LEDs will carry additional current. For hobby applications, no problem.
For hobby applications, no problem.
Would you cair to defend that remark? Last time I looked the laws of physics were the same if you are doing a hobby or not.