me too. except for the tub. i find that if you run the water fully it runs right over the drain and isn’t allowd down so i either run the shower head, or fill the tub a few inches and let it go while running the lav. and flushing the toilet.
I did one home where the bathroom sink would stop flowing when the kitchen faucet was turned on. Both faucets would stop flowing when toilet flushed and you could hear the water being sucked back in the pipe. Way undersize supply piping.