With a low lot, in theory you stand to gain more from hanging at upper angles. You may also want to look into fulcrum hanging.
To the original poster, you shouldn’t be in such a hurry. If you just began hanging and have focused on BTC, that is great. But one month is not long enough to expect gains. This is a very slow process. Also, it is suggested to not hang over 20 minutes as that is when tissue death can occur. So rather than extend each interval, try to add sets. Also, if you can, try and get at least one set in every single day. You create deformities when hanging, and you don’t want to give it time to heal and toughen up your unit.