The state of the proceedings and the need for procedural economy taken together imply a requirement for a party to present appropriate requests as soon as possible if such requests are to be admitted and considered (T 1033/10, T 375/11, T 1245/11, T 2219/12). Requests filed very late (i.e. shortly before or during the oral proceedings) will therefore be admitted only if they are prima facie allowable. The admission of new requests at a very late procedural stage (shortly before the oral proceedings) is only in keeping with the principle of procedural economy if the requests are not unsuitable from the outset to overcome the doubts as to the allowability of the claims (T 978/05, T 1731/06, T 33/07, T 321/07, T 1650/08, T 486/14, T 1322/15). As far as procedural economy is concerned, an amendment at a late stage in the proceedings is justifiable if it is an appropriate and immediate reaction to unforeseeable developments in the previous proceedings which do not lie in the responsibility of the party submitting the amendment (T 1990/07, T 1354/11).

The amended claims must not give rise to circumstances relevant for the assessment of patentability which are so new that the other party cannot reasonably be expected to address them without the proceedings being unduly prolonged (T 651/03).

Both the timing of the filing of amended claims or auxiliary requests and the difficulty entailed in examining them are important criteria for deciding whether they can be admitted to the proceedings (T 397/01): the later the requests are filed, the less likely they are to be held admissible (T 942/05); and the more complex the issues raised by amendments and the later those amendments are filed, the greater the risk that the remaining time is insufficient to consider them properly (T 81/03).

In T 412/12 the appellant filed a new auxiliary request at the last possible moment in the oral proceedings, namely after the fourth auxiliary request had already been discussed and found allowable. The board held its tactic of moving little by little towards filing a new auxiliary request "at the last minute" to be neither justified nor fair towards the other parties – all the more so given that a request had already been found allowable – because admitting that request would have prolonged the proceedings substantially. Such a delay would have also run counter to the need for procedural economy at the stage that the proceedings had reached.

If an objection (made by a party and/or by the board) is not fully understood in a particular case, it is then, at the very least, incumbent on the party having difficulties in understanding an objection to indicate this at the earliest possible stage and make the appropriate effort to have the objection clarified. A lack of understanding alone cannot justify postponing amendments to a party's case until a later stage in the proceedings (T 1033/10).