Leads and lags appear as mystery elements in reports. I prefer to add them as separate activities to make the lead or lag, plus dependencies, clear. I am thinking about the mouseover info you get in Web sites.

When leads and lags are not identified as separate activities, there are mystery gaps and overlaps the project manager has to explain to everyone else.

When leads and lags are identified as separate activities, the overall chart/report is too big and too complicated.