Yup, the relatively small credits reward you get from exobiology isn't worth spending hours and hours over. Much more rewarding to do the Cartographics stuff from space. I like to make a change from that when the opportunity arises though by exploring planet surfaces when any promising landable ones show up. Ill try to be more efficient in future though, knowing what I know now...
Well stratum is a decent payout (over 800K each isn't it) and not too hard to locate. Otherwise, yes you can make more from staying in space when exploring I feel.