Probably more aimed at small companies than large, but what is the general consensus on speaking with your employers about areas of their business that you feel need improvement?

I think a lot of times in large companies, you can see how things are going bad. But some companies are so monolithic that trying to point out where something can improve becomes you against tradition. For example. I remember at an old job people were compiling finance reports from a 100,000+ line excel document that itself was retrieved from Oracle. I remembered thinking that "hey this method is shit." But even though I proposed fixing it no body wanted to change what they were already doing. Basically, talking about business improvements is a gamble. It may lead to a promotion if you can demonstrate a viable solution or you may end up seeing just how deep this rabbit hole goes.

I think for small companies the answer is an emphatic yes, and is one of the reasons I love and prefer working for small companies. You have the power to make a difference by providing another opinion, taken from a different view, one that a CEO/MD/Founder probably can't see; just because you're probably more involved in something than they are. For the most part, I've found small company CEOs receptive and thankful for the feedback. It helps ingrain you into the company, and you become an important part in its running. In turn, this makes you feel more worthwhile and ultimately happy there. It's a win-win situation (usually!).

Of course, sometimes it's not like that. There is nothing more frustrating than watching someone in power making mistakes which you have foreseen, or thought you could prevent, especially if you have pointed these out to them. I've also experienced this. You have to leave, because otherwise it's just so frustrating. One of the reasons I don't like working for big companies, it's just not possible to keep those lines of communication open to everyone and stuff gets lost.