THEORY: irregular conlangs

Hejsan allihopa. (Hello.)

In Sociolinguistics class today we had a discussion
about irregular forms in languages. You know, strong
verbs and adjectives, etc. "Go, went, gone".
"Good, better, best". Obviously it is the most
frequent verbs and adjectives that are irregular.
The question is why. We got the explanation that
because they are so frequent, you can produce it
faster if it is a lexeme rather than a conjugation.

That is, "went" is a whole other word than "go".
You need the word "went" and then you pick it out
from your brain immediately. If the past form of
'go' would have been 'goed', you would have had to
first think of 'go' and then put the suffix '-ed'
to it. Therefore 'went' is faster and more
economic. IMHO this seems reasonable. (Although I
guess I should have to ask my Psycholinguistics
teacher first.)=20

It seems to me that there should be some correlation
between frequency and irregularity. There should be
a border somewhere, where a word isn't so frequent
anymore that it becomes irregular.

Anyway. My two questions. What do you guys think
of this? And do you do this in your conlangs?
AFAIK, in most languages the copula verb is
irregular, but most conlangs seem to be very regular.
Am I right or wrong? I know many of you (as I once)
want an extremely logical language, one that you
have to invent because there aren't any logical=20
natlangs. But those of you who persue a natlangy
touch of your conlang, how far do you go in your
irregularities?

Daniel Andreasson
daniel@conlang.nu
http://conlang.nu