Many people here would say that it is not advisable to do both at the same time - that is how an injury could happen. I personally have done both at the same time without any negatives or great positives. I got better results from extender, but it causes lymph blockages for me, so I switched to hanging.
That said, I’m interested to dig into why you aren’t seeing any results from just hanging. From what I’ve read, hanging is typically considered the fastest and best way to increase length - there are many other ways, so for the readers of this, please don’t flame me.
Are you using heat?
How much weight have you been using?
How many hours per day and week have you been hanging?
Suggest reading the progress thread of 5.5squared. He’s had amazing gains with a calculated, but minimal approach. He patterns his method after Kyrpa, CBateman and Igigi. That’s the method I am now following.
Basically, do one hour per day five days per week. First 20 minutes at lower weight to get the initial stretch, add weight and use heat for 30 minutes, stay at the same weight and cool down for 10 minutes without heat. This can be done with lower weights and consistency.
Everyone is different, so hopefully this is useful to you, and like thisistheway said, consistency with whatever approach you take seems to be the most important thing.
Mar21 - BPFSL: 6.5", BPEL: 6.5", NBPEL: 6", MEG: 5.5"
Jan22 - BPFSL: 8" (cold), BPEL: 7.5", NBPEL: 6.875", MEG: 5.5"
One Day - BPFSL: 9.5", BPEL: 9", NBPEL: 8.5", MEG: 6"