Incorrect information.

At LGA, DL uses three terminals. The third is the old Marine Terminal (now called Terminal A) where flights to Chicago and (apparently important for this OP) DCA flights operate. The change from C or D to A is a slow, brutal bus ride which can take much too long and IMO is something clearly to be avoided.

In addition, I consider any itinerary with a connection at LGA to be complete madness. The delays and IROPs are so prevalent that there are too many days when the arrivals and departure boards looks like some sort of stupid mish-mash. Yes, I use it for O&D but I know to make allowances for LGA since its sheer convenience to the City (15-20 minute cab ride to my apt) makes up for the other nonsense.