There is a way on the Grid View on ResDiary Plus, where you can make bookings without having to go through the full booking process:

Click on the table and timeslot you want to book, as you can see below the blue dot is telling me which table and timeslot I have chosen. 

Not only that it takes me straight through to entering a customers details - The diary knows that you want that table at that time and it will assume that the cover count is the maximum on the table

If you need to edit any of the details as you may have made a mistake you can do so via clicking on the header and a dropdown will appear, if you click on any of these it will let you edit the specific information:

If you are looking for a different cover size for this table the fastest way to do it is to make the booking and then click on the actual number of covers and do a 'change covers on the fly'