A politician says "once in a generation". In that time a lot of things can happen. Think back a generation (about 30 years) and of the big things that have happ

A politician says "once in a generation". In that time a lot of things can happen. Think back a generation (about 30 years) and of the big things that have happened. The SNP leaders, when making this statement, were all well over 30 and hence, knew that big things happen in that time. That's why the changes you might say would lead to re-evaluation do not.