Duration question is interesting! For me it applies on tapes. If I am going to spend, lets say 10-15,- for tape, I would like to know is it C-10, C-30 or C-60. No matter how good C-10, I would be probably considering do I NEED 15 euro C-10...
But, LP, CD... I don't think there has ever been moment when I was disappointed that album was too short? In recent times there has been a lot of good 30 minute noise albums. It is great for me. Even if format would allow 70+, I do not think it is necessary to fill in maximum amount of duration, just good album.
It is interesting question, is someone thinking if seeing 25 min or 30 min noise CD, that this is not enough for price of full length!