I had a look at different operas and songs with piano accompaniment. I noticed that one often does not connect beams that one usually would in instrumental music (such as four sixteenth notes in 4/4), except when the same (part of) word is used for multiple notes. Is this a general rule or are there other possibilities as well? Is this not a confusing way of notating music for classical singers?
Consider for instance following schematic example where I is shared by the first two notes, and want and to only have one note.
Comment to Tim's answer
Indeed, but there might be cases where not beaming notes might in my opinion make the rhythm less understandeable. The first thing I wood do when having to sing following example, would be to rewrite the rhythm by beaming everything per quarter note.