For the legal definition of "frivolous", yes. For stuff like asking for additional EPA assessments which change nothing, but add another year and cost $$$, not so much.
As an example, the nuclear storage facility was delayed, and ultimately cancelled, because the geologic analysis had only established the stability of the ground for the next 800,000 years, and the lawsuit demanded that it be extended to several MILLION years into the future. ...and they WON.
Absolute INSANITY.