I maded it to NG+11 I think, once you get Phase Time X you don't need to do go any further. Actually basically the last run I didn't buy anything other than some ammo, using whatever I found on the way and since you can have Phase Time on all the time, there's no challenge (other than the final space battle).
I'm done for now at 136 hours played, next time I get into it, will definitely start a fresh character!
My body's just a flesh vessel for an immortal being whose name if you heard it would make you lose your mind.