“The DOL advises plans that certain inadvertent and harmless errors will not trigger de novo review. The Second Circuit saw no reason why courts should not also tolerate such minor deviations, but cautioned that the deviations should not be tolerated lightly. Accordingly, the court held that when denying a claim for benefits, a plan’s failure to comply with the claims-procedure regulation will result in the claim being reviewed de novo, unless the plan has otherwise established procedures in full conformity with the regulation and can show that its failure to comply was inadvertent and harmless.” [Halo v. Yale Health Plan, No. 14-4055 (2d Cir. Apr. 12, 2016)] (Wolters Kluwer Law & Business)