Countblank for handpicked cells

I have a complex schedule in a spreadsheet. There are five sheets for the five days of an event. On each day, there are multiple times and rooms being used. And within each day/time/room session, there are multiple roles to be filled.

For each session, I have cells with the positions (e.g., Volunteer) with a cell to the immediate left in which to type someone's name as I recruit volunteers or other roles.

Here is the problem:

I would like to have the spreadsheet automatically count up the empty slots for each of the several types of roles. For example, I would like it do run through the five sheets and count up all the empty cells needing a Volunteer.

I understand that you can use CountBlank for a column, row, or box of cells. But, that won't work for me.

Is there a way to handpick specific cells and name them something like "VolunteerSlots" and then run CountBlank using that as the range? Like, could I ever use something like this: =Countblank(VolunteerSlots)? That would ideally then count the handpicked cells to see if they are empty or not.