... I'd conjecture that as one's exposure to and training in the methods of science increases, then one's reliance on spiritual and theistic views tends to decrease.

What has a foothold is doing physical science, which tends to preclude doing spiritual and theistic religious stuff -- unless one is a
hardcore religious fanatic (I'm using this term loosely) and really really smart. In which case one might invent ingenious rationalizations for one's spiritual beliefs, rather than admitting to an emotional need for some sort of elaborate invisible friend(s) structure.
Adherence to spiritual-theistic religious beliefs is very much an emotional, and something of a social, thing I think. That's why some, otherwise quite rationally oriented, scientists want to cling to beliefs that most other scientists have dismissed as unwarranted (and unnecessary).