I never really cared for Ipa, unless some other factor required it.
Clay always was enough prep, and I have never had problems.
That being said, every situation is different.
I would defer to Jeans knowledge if you want to get perfect glad.
Now, I am not sure if he is saying to use Ipa or eraser everytime, or
if he is suggesting that that is the method for a higher quality shine.
I personally have never had the problem of left over product, or residue
as long as I stayed with the optimum line. For me, they work great together.
Your results may vary. Some people may put too much, some not enough.
For me, Ipa is only used for really stubborn spots, as I don't like the way it
messes with the paint on my Subaru. Your cars paint is another reason that
your work may vary from others. No doubt that using IPA should be in your
box of tricks. The question is: do you need to use it 100 percent of the time.
For me, going back over the entire vehicle again adds much labor.
I personally go :
ONR,
Clay with ONR as lube strength,
Compound or GPS,
Then Finish applied if I used compound.
Also, if looking to get glass, just find some products that you like,
use them often and refine your personal method. I have seen some
amazingly different results from same products just because someone
understood how to work them better.
For me, abrasive isolation helped much, add it gave me some things
to focus on during polishing.
