Writing as a Conservitizing Agent in Language

Good day to all ye merry ladies and gentlemen!

I have heard that when a people develope a writing system for their
language, it tends to conservatize - slow down in its evolution. However, I
have a question about how pictographic writing affects the rate of change of
a language, since whereas an alphabetic system would have a more obvious
conservatizing influence upon the language, it SEEMS at least to me that a
pictographic system (eg kanji) would be much less influential since they
don't tend to have related sounds:

Unless someone tells you how 山 (Chinese character for "Mountain") is
pronounced, it tells you nothing by itself how it might be pronounced - and
it is your own idiolectical pronunciation of the word in question - whereas
seeing M OU N T AI N (and having learned the general rules of pronunciation
of these individual characters, I as an American English speaker will upon
first encountering the word, manage to sound it out and produce a word that
faily well resembles the other dialects of English . . . ARGH, I probably
just contradicted myself somehow.

Anyway, my question is this: does a language with a pictographic writing
system tend to change faster than a langauge with an aphabetic system of
writing?