Phrase marks in Mozart

[slobone]

I was always led to believe that phrase marks in Mozart should be taken literally. That is, when you come to the end of a phrase, you lift your hand off the keyboard, if only slightly, before playing the next note. You don't make a legato connection.

But today I was browsing through an urtext edition (Peters), and I notice first of all that Mozart is very inconsistent in his articulation markings. Some pieces have a lot of them, others have almost none.

And he puts phrase marks where I would not expect to see them, for example between two measures of a continuing Alberti bass that is otherwise not of any special interest. Does he really mean I should lift my left hand off exactly there, and nowhere else?

Does any of this have to do with differences in sound between a fortepiano and a modern piano? How literally should I be taking these markings?

[nyonyo]

I was taught by my teacher to observe the phrase marks very strictly and not to connect between measures, unless it was noted that way. I like the sound too, it sounds sophisticated and very clean. By the way, my piano teacher is concert pianist who went to Moscow and Julliard, so I can trust his opinion.