I do a few of the bigger properties on my rounds at winter time usually a few just before and after xmas , helps with cash at that time of year as windows can be a pain ,prob do a grand a year in gutters , its spends i see it as ,, or buys new poles etc
Unless your flat out 5-6 days a week you can fit in a few gutter cleans here and there , just price them right as its horrible work
I do them with a friend who has a triple ladder , we share the work and foot for one another usually make about £35-40 an hour each