i'm trying to create a smart work schedule for my workplace. Due to nature of our work sometimes one person has to be responsible for more than one lab. Some splits are possible to manage and some aren't. I have a ready sheet (called Grafik podzielony) that processes information from another sheet (Grafik). Work is divided into 3 shifts: 1st one 7:00am-11:00am, 2nd one - 11:00am-2:30pm and the 3rd one from 14:30pm onwards. I'd like to highlight cells that contain substrings occurring more than once in a particular timeframe (e.g. 7-11am). I've tried to do this in numerous ways and yet i've failed miserably. Any help really appreciated.

Here's an editable like to the spreadsheet