it seems rude not to knock when your on their property. we used to, but found it wasted time if they end up talking etc, tho sometimes they pay you there and then too.
we found a lot found it strange you knocking, like it didn't matter, just get on with it already.
so we just knock on a couple of older ones cus they like it/probs with nerves. made me think tho whether we should be knocking more, don't even have to hang around, they will look out and see the van/reels.
but I guess seeing as it's not broke, and it's working not knocking....