Dear @Pch and @Paul_Danyliuk. Your remarks got me thinking and I have realized that I probably constructed table with incorrect logic. What I tried to do in the column “Rooms” was to keep a tab of how many rooms are booked in total for that day (I have corrected it now to represent it with the formula and introduction of “hour slots” column), thinking that in such way I could tally up the numbers easier. But as @Paul_Danyliuk pointed out, - it is a wrong approach to start with and required deduplicating rows that would then miss other important data. So I will try to think of another logic to count number of rooms slots reserved for every day now using count of hour slots for every day. Probably much easier approach 
Thanks a million to both for helping out.
@Paul_Danyliuk and @Pch - if you could have a look at Calculate occupancy rates for a business when dates with zero activity are not in the data table and help me with some sort of similar insights, I would truly appreciate that.
Kind regards. Vytenis