  The effective field theory (EFT) framework is a precise approximation
procedure when the inherent assumptions of a large-scale separation between the
Standard Model (SM) and new interactions alongside perturbativity are realised.
Constraints from available data might not automatically guarantee these
circumstances when contrasted with UV scenarios that the EFT analysis wishes to
inform. From an EFT perspective, achieving sufficient precision in navigating
the alignment or decoupling limits beyond the SM scenarios can necessitate
moving beyond the SM's leading, dimension six EFT deformation. Using the
example of Higgs boson mixing, we demonstrated the importance of
higher-dimensional terms in the EFT expansion. We analyse the relevance of
virtual EFT corrections and dimension eight contributions for well-determined
electroweak precision observables. We find that when moving away from the
decoupling limit, the relevance of additional terms in the EFT expansion
quickly becomes relevant. This demonstrates the necessity to move beyond
dimension six interactions for any scenario that contains Higgs boson mixing.
