No one complains about the length of time audience members are expected to sit through Mahler's symphonies, of which eight out of ten occupy more than one hour - or indeed Bruckner's, of which nos. 2 - 5 and 7 - 9 do likewise.
I can relate to that - since we went up to SPb last week to see & hear the Mariinsky do FRAU OHNE SCHATTEN, uncut. They announced 4.5 hours for it, including intervals, which seemed unrealistically tight... so we booked the 01:58 am overnight sleeper train back home to Moscow, as the midnight express looked dicey. In reality the curtain came down at 23:50, after an 18:30 start. With my head stuck in the technicalities of turning the set-changes round in time, this still seemed rather lax... but wiser counsel came from my colleague on the trip. "She's knackered, after the Act III finale music - it's tougher than the end of Valkyrie, and now she has to sing non-stop through Act IV. She has to get a break." Sadly I feel Strauss is the guilty party here - unrealistic writing on his part, considering he was an opera conductor himself.