Be always doing something
Replace "doing something" with a verb, and conjugate:
e.g. "My boss is always shouting at me."
"Always" cannot be replaced with other adverbs of frequency - showing that this is a special usage.
Using copular be in the progressive supported by auxiliary be sounds a bit weird; e.g. ?"you're always being late" - we would usually drop the progressive aspect and just say "you're always late", or we could circumlocute and use a dynamic verb, e.g. "you're always coming late".