On the website of Chiltern Seeds in the UK, I note this in the description of some of the Hollyhock cultivars -

"Sown early they will flower the first year, but the finest plants are produced when grown as biennials..."

My sense is that this is correct, but I haven't seen this issue discussed or acknowledged much. I'd love to hear others' experiences with this. In 2019 I had a Hollyhock 'Nigra' that grew as a biennial. The first year, leaf growth was quite substantial and the second year the flower stalks filled in beautifully, the blooming proceeding up the stalk fully with many flowers blooming closely together in the same area at the same time on each stalk, with some but minimal gaps.

This year, here's a different plant, grown from a small nursery plant that flowered the first year, overriding its natural bienniality. Compared to the 'Nigra' from the previous year, the mature plant is smaller, the number of stalks fewer, and those that do exist have smaller number of blooms on them, with more and wider gaps.

It seems we do sacrifice size, floriferousness, and especially fullness of the blooms on the stalk when we force the plant to flower the first year, as wonderful and desirable as that is.

But I may be wrong and would like to hear others' experience with this.