When considering an application to extend time, the Claimant and the Respondent are usually called to give evidence. For example, if it is being argued that the Claimant was late submitting an ET1 because he thought that internal procedures were being followed (a defence under the Employment Act 2002) then the Claimant must give evidence that he thought that matters could still be resolved and at least that he was engaging in an internal procedure. In the same way, The Respondent's Appeal Officer may be called and cross-examined with a view to proving that an internal procedure was being pursued.
This may well take a few hours and even a day to sew up. A new judgment however means that need not be in any particular form, thus saving time. The parties may deal with the matter by submissions if they wish!