How not to waste disk bandwidth

In the Windows 7 search boxkeywords are case-insensitive, but Boolean operators are case-sensitive.  Typing

System.FileName:~=".doc" AND datemodified:‎1/‎5/‎2016

works fine. Typing

System.FileName:~=".doc" and datemodified:‎1/‎5/‎2016

doesn’t given an error message or a warning — it just burns a lot of disk searching and finding nothing. Live and learn!