I personally wouldn’t prioritize saving the head over completing a 3 block because I’ve won plenty of games where I was tenpai waiting for the head and I’m able to adjust what I’m waiting on to something others are more likely to discard. Of course I wouldn’t intentionally aim for tenpai waiting for the head but if it plays out like that at least I can mess with people by waiting on a tile in a riichied player’s discard.

Edit: JPML's play like a pro episode 3 explicitly teaches against committing to a head instead of just completing the block. Episode 5 further expands the idea by not even having a pair at tenpai in their second example.