FCFE forecasting formula when to use?

The following formula appears to be used in forecasting FCFE but not necessarily in all instances:

NI - (1-DR)(capex - depr) - (1-DR)(Inv in WC) = FCFE

Do we always use this when we are forecasting or is there some other reason on why we use this formula??

I only use this formula when the vignette/questions specifically asks for FCFE when the firm is striving for some target DR (Debt to Asset ratio). Otherwise, it’s best to stick with the traditional FCFE formulae.