Had no problems on Arvia last month. Booked the 2 Black Tie nights online before we sailed. That was for a table for 6, both at 6.15. Once on board we dined in either of the two MDRs each night. Here we used the My Holiday app and it was excellent. Usually joined the virtual queue about 6.40. and only once did we have a wait longer than 30 minutes. We factored in the wait time so that we could finish getting dressed for dinner/enjoying a drink on our balcony. On most nights we were booking for a table for two...no sharing. Pretty much seamless...but get used to the numbers in the virtual queue going slowly down from, say, 30, then going from e.g. 20 in the queue to a 'ping' and a Your table is ready' message! So virtually every night we walked into the MDR between 6.50 and 7.15. Suited us really well.