Checking text across a range of cells

Hello, I'm an Excel noob so this might be blindingly obvious but I've tried Help and Google, all to no avail.

I have an Excel sheet set up with 6 columns:
Col A contains a user-entered date.
Cols B-E each contain a drop-down that the user can set to 1 of 4 options.
Col F (I want) to show a date based on Col A & the results of the drop-downs.

The drop-downs contain (in order of importance): "Immediate","Urgent","Routine" and "None". If any of them are set to "Immediate", the date in Col F should be Col A date+2 days, if any set to "Urgent" it should be Col A+14 days, any set to "Routine" it should be Col A+28 days and for None the field can remain empty.

I can enter a formula in F2 that checks for B2's drop-down as follows:

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which works perfectly for that column. I therefore thought I could just substitute each "B2" with "B2:E2" to check across all four columns but when I do I get "#VALUE!" in F2. Surely if it works in checking one column, it should be easy enough to check across 4 columns? I did have a workaround that I thought would work which included lots of nested IF's but I soon found out that Excel has a limit of 7 and it needs more than that (which seems a long-winded way to do it anyway).

Am I missing something obvious here?