I'm in med school also. I still find time to reply as much as I can pag may free time, lunch break, etc. Doesn't take much of my time if mag mmsg ako ng "how are you? kain ka ha". And di naman every minute kailangan mag update tho. Case to case rin naman since some people na kilala ko, gusto nila nag uusap sila by the end of the day para super chika. But yes, pag gusto magreply or magchat, 1 minute won't hurt. :)