I was told at university that to say "Du bist spät!" (to a student who is late for class) is incorrect and that it should always be "Du bist /zu/ spät!"
Is this true? Is there no context for simply saying "Du bist spät!"? My argument when I was told this (though really there should have been no argument as it was an Austrian who told me!) was that if "Du bist zu spät!" is the only way to say "you are late!" then how would you say "you are /too/ late!" e.g. "all the food has gone, you are too late!"...
Am I making sense?!