We live on a fairly new housing development & the builders planted escallonia hedging between all of the houses, 1-6 years ago & a lot of them now look quite scruffy (& similar in size). Don't know the type (cheapest??!!) they're very dark pinky/red. Ours were planted 2 years ago.
Early this spring neighbour to the right mentioned how untidy it was (he didn't particularly want it anyway, but we prefer a boundary) so I pruned it quite hard. It hasn't flowered this year. On the left side we left it, it flowered a bit & it still has a few flowers on it.
I thought that it should be pruned in spring as it flowers late in the year; Mr Google has many opinions on the matter, so I thought I'd ask some much more knowledgeable people .