Presenteeism is such a daft model for employment. I am not sat at my keyboard for my whole work day. I could, if forced, but I’d literally get less work done and I’d burn out so quickly as to be a liability to my employer. Half of what I do is reading technical documents and understanding them. Lots of the time that means doing literally anything other than reading more documents - they need to be digested and that means not trying to cram even more data in.