On a commercial CD you can reasonably do 78 minutes, though the durations of most folk CDs tend towards vinyl album length of 50 minutes or so.

A CD is not a CD-R; just as a DVD is not a DVD+R / DVD-R. Artistes are forever selling their 'CD' when it is, in fact, a CD-R. It's a different beast entirely, despite superficial similarities. I wonder, do people not know they're different? Or are they pulling the proverbial fast-one? In any case it's misleading under trades descriptions. Plus the fact CD-Rs are rather cool because they cost nowt to make so you can sell them for less...

And those opportunistic folk singers I must bring 'em in,
With their home produced albums, they think it no sin,
To call it a CD when it's cheap CD-R,
That'll cost you 12 quid but won't play in the car...
Honesty's all out of fashion.
These are the riggs of the time, time, me boys
These are the riggs of the time...