Doesn't really answer your question (and I don't really like the idea of constructing a static, non-polarized 3betting range where we assume villain doesn't adjust), but in position I tend to 3bet and 4bet for value on the basis of 50% i.e. if villain opens 20% CO then I'll 3bet 10%, if villain 3bets 5% then I'll 4bet 2.5%.

Obviously I'll open this up for bluffs depending on villain and adjust for positions and stack sizes. The 50% rule is also too nitty as ranges get tighter i.e. if villain 4bets a non-polarized 3% then jamming 2.6% is profitable (QQ+,AK) if we assume villain never 4b/f.

Happy for those better at algebra to rip this post apart if required..