I know the code says to never branch off of a 1/2" line. In other words here in VA it says (I think it still says) that all fixtures shall be fed from a 1/2" line teed into no line smaller than 3/4". In other words, NO 1/2" TEES. I dont run into problems say like when I installed a shower in a 1/2 bath that had a sink and toilet and just teed into the 1/2" lines for the sink to feed the shower. Cant see where someone will come in and run the sink and take the pressure from the shower! Only had one inspector that did not allow it and had to go back to a 3/4 line. Geeze! Give me a break!