For the (1+1) evolutionary algorithm with standard bit mutation, we study the sensitivity of the expected hitting time
Hp=ExT to the mutation rate. We first point out an easily overlooked formalization pitfall: the improvement event is not monotone in the mutation mask, so the unsigned (total-influence) form of the Margulis-Russo formula does not apply; the correct object is the signed endpoint difference. Second, we give an exact three-dimensional separation: two fitness functions share the entire one-step success-rate curve, yet their expected hitting times are two different exact rational numbers; hence one-step success-rate quantities do not determine the expected hitting time. Building on the runtime derivative
Hp′=(I−Qp)−1Qp′Hp, we construct computable double-residual sign certificates, prove a per-initial-state sign theorem on OneMax (for every non-optimal initial state,
∂cH<0 on
0<c<1, where
p=c/n; at
c=1 only the distance-one state is stationary), and extend the framework to non-lumpable positive linear families: an explicit non-lumpability witness, a block-interval double-residual certificate that covers all states without enumerating them, a uniform sign bound
∂cET≤−9n/16 over the whole interval
c∈[1/4,1/2] for an explicit family at all even scales
n≥8, and a heterogeneous instance certificate
Hx′≤−1/6 on 57 of 63 states across
c=1. All finite verifications use exact rational arithmetic. A bounded systematic literature search did not uncover this exact combination, although the underlying tools are well established; we therefore make no novelty claim beyond the stated combination.