I once worked for a CEO and 90% owner of a startup who did very well for himself ($30 million exit - which he got almost all of as he hadn't taken any external funding) even though he really believed this. As far as I could tell he wasn't pretending - he really believed that any feature (no matter how complex and we were working in a very complex area) could be implemented in a week. As I was VPEng this perplexed me greatly - particularly as there was a conspicuous track record of features not being implemented in the times before I arrived.
My only explanation was that his attention span was about a week - if he asked for something and it appeared in a week it was great. If not he forgot about it....
[NB This CEO was a very bright guy - and I had a lot of respect for him].