Well, partly, in the summer, I print late nights and early mornings.
I also have a very poor attention span, and rarely print more than an hour solid before taking some sort of break, whether bathroom, food, drink, marital relations, and/or forums.
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Very flexible hours is one of the perks running my small business as a sole proprietorship on my residential property.
Some folks don't understand that peace of mind can be priceless.