Peak Shearer was 3... maybe 4 seasons? If Kane can stay fit he could get 7-8 tremendous seasons. That would put him over Shearer for me.
On his day i'd take il fenomeno over Cristiano but Cristiano's had the much better career.... at least at club level. 3 top seasons, maybe another 5 superb ones vs 8 or 9 top seasons.
I mean Shearer averaged 20 goals a season over his whole PL career, so using your same logic applied to CR he had a little more than just 3 or 4 seasons.
Just because it wasn't up to the ridiculous level he showed pre 98 doesn't change that.
But anyway we are clearly not going to agree and I agree with KI, Kane is brilliant and there's really no need to put this sort of comparison on him.
Let's just see how his career goes.