Possible to match multiple conditions in one case statement?

You can use the ;;& conjunction. From man bash:

               Using ;;& in place of ;; causes the shell to test
the next pattern list in the statement, if any, and execute  any
associated  list on a successful match.

Ex. given

$ cat myscript 
#!/bin/bash
NOW=$(date -d "$1" +"%a")
case $NOW in
    Mon)
        echo "Mon";;
    Tue|Wed|Thu|Fri)
        echo "Tue|Wed|Thu|Fri";;&
    Fri|Sat|Sun)
        echo "Fri|Sat|Sun";;
    *) ;;
esac

then

$ ./myscript thursday
Tue|Wed|Thu|Fri

$ ./myscript friday
Tue|Wed|Thu|Fri
Fri|Sat|Sun

$ ./myscript saturday
Fri|Sat|Sun

For more information (including equivalents in other shells) see

• Can bash case statements cascade?