⁵⁶Ni distributions for models explored as part of this work. Panels show the best matching models to the light curves beginning approximately five days after explosion (i.e. excluding the early bump) of SN 2018oh (left) and SN 2017cbv (right) as black solid lines, which we consider as our fiducial models. Dashed black lines show models that have more extended ⁵⁶Ni distributions compared to our fiducial models, but are otherwise identical (i.e. the same density profile and ⁵⁶Ni mass in each case). Coloured lines show ⁵⁶Ni shells of varying masses. Each shell is centred on a mass coordinate of 1.35 M_⊙ and has a width of either 0.06 or 0.18 M_⊙.