But often in music composed in the Renaissance and early Baroque period (as in the above picture) alla breve has 4 half notes per measure. This makes the counting and playing of such music quite problematic for a simple reason - a modern player uses the counting in quarter notes more often than in half notes.
Today's sight-reading piece - Ricercare No. 1 (p. 1) by Costanzo Antegnati (1549-1624) is exactly such composition. Antegnati was an Italian organist, composer and organ builder from the famous family of organ builders who wrote L'Arte organica which is a treatise about Italian organ registration and organ building tradition of the time.
In order to facilitate counting, I recommend you do it by first glancing over the score and mentally noting where beat 1, beat 2, beat 3 and beat 4 is. Observe how sometimes one voice migrates from the right hand to the left hand part and vice versa (as in m. 7). Use articulate legato touch because this is early music.