I think NASH is a fine base line and for use against an unknown villain if used as an exclusive guide.
Math is obviously the fundamental of poker but ranging makes the math viable.
So I feel like gut needs to be a compass for the application of math.
Edit-
No while I am familiar with it I dont know the ins and outs at all. So take this as an op ed.
nash is just what you use when other exploitable strategies are not available-ie. if a min raise will work-then its better than a shove, if a limp stab will work its better than a shove, even the ole limp call is better in some situations