The final getsuga

[drgnx]

I quote "You're going to have to tread the ground of thousands of years that you have yet to experience". While what I said may not exactly be what this says I do believe I got the general idea of it which is to to be able experience all the training he has not had yet so as to be able to achieve his maximum potential

Here is the link for reference: http://read.mangashare.com/Bleach/ch...8/page011.html

If you read the whole chapter you'll see it is a practice that is thousands of years, Ichigo himself had 3 months to learn it. The technique of learning/training may have been refined over thousands of years, but that does not add up to thousands of years of experience. And since Isshin is teaching Ichigo directly, the added value of the additional experience is going to be minimal in comparison.