I wouldn't put it that way...

the longer one takes to enter therapy for PTSD then the more time to develop bad habits of coping that have to be replaced which takes more therapy...

PTSD being an anxiety disorder causes us to quit thinking rationally. If it develops at an early age then rationality hasn't been developed yet and a distorted view of the whole world begins. Bad habits of thinking, being unworthy, not trusting, hypervigilance all impact your way of life. Unraveling all the bad habits and replacing them with rational, positive ones takes time.

There is no cure for PTSD but therapy makes life livable with it.