From you description, it is not quite clear what you are referencing. One thing to remember is that in any legato patch, if there is a gap between notes, the release sample of the previous note will sound again as an individual note at the start of the new note. Leaving any significant gap between legato notes will likely cause problems.
You might find VI Pro 2 to be of use, as you can vary the speed of the initial legato attack (and create new patches with alternate speeds). This could be of real use particularly in chamber strings, where there are no fast legato patches.
Also - although perhaps OT - in some types of bowing a "pulse" will result even if the bow direction is not changed where a player will play consecutive notes on the same bow stroke, but add a slight attack as it were to each note, even though the notes themselves remain connected in a legato fashion.