In absolute numbers, no more reliable than the companies feeding them the raw data.
In terms of the relative trend, reasonably accurate about the direction of the overall trend (more layoffs), but these days not terribly accurate in the rate or timing of layoffs.
Then it is all further complicated by the conflicting and opposing economic forces - suppresed interest rates and weak fundamentals in the in the US vs profit growth offshore and the shift from a manufacturing to service based economy.
All make for shifting and difficult corporate planning which is reflected in the CG&C reporting.