It feels as though he invicorp 'relaxes' the tissue ,so allowing the pump to work more effctively.
I have found that injecting after a hot bath is best. If there is not enough time for this, a quick pump gives me a bigger target. I haven't had any complete failures for the jab as yet, but sometimes it works better than others. Maybe this is down to poor injection technique.
What works for me is to wait until the injection is working fully- which takes twenty minutes or so, and then use the pump and apply a ring. This is good for half an hour until the ring needs to be removed. If we need (want) more time, I wait another half an hour (this time can be used productively) and re -pump. The injection seems to be good for around two hours for this in my case.
Loss of sensitivity is an issue for me with the tight ring, but its definitely much better than nothing.