I can't say about other Hippieastrum species, but at least the hybrids so common in the market are incredibly adaptable. Regardless of their ancestral backgrounds including dormant periods or not, yes, often the most foolproof method of bloom is via seasonal change (of which multiple factors could be used to achieve the goal). However, seasonal change is not required, or at least a seasonal change that is gardener detectable.
Yet, the "your mileage may vary" caveat is valid. Every true gardener knows, that changing even just one factor in a plants environment, intentionally or not, may alter the needs or growth of the plant. And this is true for the common amaryllis, too.
