Even if you understand the process, you can't productively suggest changes until the client is ready to hear your input. This means you have to "pay your dues" in whatever coin their corporate culture requires--putting in the time, finishing a project, making a contribution, whatever--before you open your mouth.

I would still argue that time is not a major factor. You have to wait until they are willing to be receptive to your comments, but it's amazing how that someone who has worked on the systems for 7 years as a developer / maintainer / user will be given less consideration than a contractor who has been brought in, and has spent less than 2 weeks looking into the situation, and doesn't even understand the technology involved. (where of course, you've been told that they're a subject matter expert on iPlanet Web Server, ColdFusion, Solaris, and Sun Cluster ... and yet they mention they had to remember those commands like 'mv' and 'cd' when you're in a meeting with them).

Some people are receptive to change, and some people aren't. Sometimes, you'll make suggestions in a meeting, and they'll be criticized, only for the same person who criticized you to bring it up a few months later, and try to present it as their idea.

In the case of contracting, it's an odd line -- you've been brought in to reach some end goal. Sometimes, you've given liberty to design the whole solution, and sometimes, you're just there to build something according to specifications that were made without your input. Your suggestion may provide benefit, but it may replace some other major change that is where the other person has made their reputation. Or, it may be that you've stated something so obvious that the higher-ups would have to wonder why no one else has ever suggested it.

Personally, I hope to never have to deal with these issues again -- there are too many people out there who are focusing on what's good for them, and not what's good for the company at a whole, or what's good for the customers of the company -- they're just too obsessed with running their own little fiefdom well, so they can get their next promotion / raise / whatever.