Reports suggest that the centre core of the FH launch crashed because it couldn't get the necessary three engines relit. If this isn't a misunderstanding (there was something about the shrapnel taking out two thrusters of the drone ship, which might easily have led to confusion) why did it need three engines. I know F9 boosters sometimes land on three engines as a fuel-saving device, but that seems like an off choice for this mission, where they had no specific target orbit. Is the core that much heavier? Or is there some other reason?
The last mission before the Falcon Heavy tested a 3 engine landing burn. They did not have an ASDS underneath it, since it launched 6 days before the Falcon Heavy mission and to get the barge back to Florida, unload, and then back to station for a landing would have delayed the flight.
But they launched the SES16/GovSat1 mission with legs and tested a three engine landing burn regardless. They were testing to see if they could do it, since it saves fuel by avoiding gravity losses.
The less time you spend decelerating the less fuel you use. So a fast landing is more parsimonious on fuel.
The center core needs more fuel to slow itself down since it is going faster than the side cores, and thus this was an experiment to see if they could land it with less fuel.
Alas, they had a TEA-TEB ignition issue. This is interesting as they have landed 23 or so cores so far, successfully and all the engine restarts have been good.