Depends what you want to do. For trad and multipitch, generally yes a 50m is fine. For some sport, no. For instance many of the longer 5.11 and 5.12 sport pitches at Skaha require a 60m or 65m for lowering off.
Also many of the fixed chain raps in the Bugaboos are set up as follows: for the easy route/via normale descents, such as coming off the Kain Route, a 50m is fine as the stations are set 25m apart. But to get off harder routes like the Beckey-Chouinard you'll need 60ms or better, double 60ms.