There are two kinds of design patterns: architectural patterns (e.g. MVC) and language patterns (e.g. Iterator). In the language I use for work, C#, we have to use a lot of both kinds of patterns. Often the "all code must be in a closure or a method" way the language works gets in the way (I can only imagine it's much worse in Java). In 100k LOC, I bet 25-30% of it (random "from the gut" guess) must be language patterns (e.g. visitor).
When you realize that nearly none (if any at all) of the language patterns are needed in Lisp you realize that in 100k LOC you only work with the problem. It seems to happen to me pretty often that I run into situation where there are two possible representations of something, both having problems and I realize that in Lisp I wouldn't have even noticed the situation at all because I could have used a more natural solution right from the start (CLOS' generic function approach makes all the difference in the world here).
Keep in mind I've used C++ and its descendants longer than I've used lisp.