It's about that time of year again. Another fiscal year has ended for many mutual funds, which means millions of annual shareholder reports are currently being stuffed into mailboxes throughout the land.

If you're like me, then you probably stack them up neatly with every intention of reading them, only to throw them all away unopened a week or two later.

If you're not like me, then you probably don't even bother stacking them up first.

And then there was one
I've never seen the statistical data, but I strongly suspect that the majority of the country's 91 million mutual fund owners just don't find the time to read these things religiously.

It's not that we're apathetic, or unconcerned with how well our investments have performed. But let's be honest -- most of us simply find better things to do. Besides, isn't that one of the major selling points of mutual funds -- that we don't have to stay on top of them at all times?

To be sure, mutual funds require far less oversight than an actively managed stock portfolio does, but that doesn't mean they can be left on autopilot year after year. Taking just a few minutes to read through an annual report will let you know whether you might be drifting off course.

With that in mind -- and because there's nothing good on TV tonight -- I have decided to actually crack open one of mine and take a look.

No news like good news
In my hand, I hold this year's annual report for American Funds Growth Fund of America (FUND:AGTHX). This fund is the largest in the country, so the odds are good that you might have the same report lying around somewhere. If so, turn to Page 1, and let's get started.

Front and center, you will notice that the Growth Fund of America delivered a respectable return of 9.7% over the past 12 months, topping the 8.9% gain of the S&P -- as well as a few other benchmarks that are used in measuring its relative performance.

The fund can make the same claim over the trailing three-, five-, and 10-year periods. In fact, over the past decade, it has outrun approximately 98% of its peers -- with less volatility and stellar tax efficiency.

And since inception in 1973, shareholders have enjoyed a dazzling 15.1% average annualized return, good enough to turn a modest $10,000 investment into a shade more than $1 million. Meanwhile, the same amount left in the S&P over the past 33 years would now be worth less than half of that -- around $396,000.

That difference really stands out on a chart on Page 4. Unfortunately for shareholders, though, success always attracts assets -- more than $150 billion in this case -- and excessively large asset bases can become somewhat unwieldy. Still, the fund looks nimble enough at the moment.

Two steps forward
Skipping ahead, we see that management has been kind enough to supply managerial profiles, some general market commentary, and a scaled-down attribution analysis -- a discussion of what worked and what didn't.

It certainly didn't hurt that the fund picked up a few shares (around 8 million or so) of Internet juggernaut Google (NASDAQ:GOOG), which jumped more than 32% for the fund's fiscal year. Tech bellwethers Oracle (NASDAQ:ORCL) and Cisco Systems (NASDAQ:CSCO) weren't far behind.

Management's preference for energy stocks (14% of assets) also paid off handsomely, with companies such as Schlumberger (NYSE:SLB) surging more than 40% on a wave of higher crude-oil prices.

Of course, with nearly 300 stocks, it shouldn't be too difficult to cherry-pick a few big winners -- but those all happened to be top-10 holdings.

On the downside, the same high oil prices that boosted Schlumberger anchoredCarnival Cruise Lines (NYSE:CCL), whose shares sank 15% on the year.

On the whole, it was yet another market-thumping year for the Growth Fund of America. However, if you hadn't checked, you wouldn't have known whether the fund had tanked or lost a key manager or something similar, so it pays to at least flip through your annual reports before you unceremoniously toss them in the trash -- if for no other reason than to get an updated look at the current portfolio.

Checking the gauges
Understandably, once you've done the requisite homework and background checks on a mutual fund, it's easy to sit back and assume everything will go according to plan. However, that type of hands-off mentality can be costly if something goes awry. A little routine maintenance goes a long way.

Of course, any manager -- even a luminary like Bill Miller -- can have a temporary slump, so don't sever ties with a solid fund because of a bad quarter, or even a bad year.

However, if the longer-term returns suggest mediocrity, why not consider an upgrade -- particularly if the fund carries an above-average expense ratio?

There is absolutely no reason to overpay for underperformance.

Champion Funds chief Shannon Zimmerman insists on doing the precise opposite -- finding those select few funds in each category that offer rock-bottom expenses and consistent chart-topping performance. To date, 96% (43 of 45) of his recommendations have made money for shareholders, with an average return of 25%.

If you spot a problem with one of your funds, then disengage the autopilot for a moment, and take a free tour of Champion Funds. Click here for more information on a 30-day trial.

Fool contributor Nathan Slaughter wouldn't mind switching his car to autopilot, but never his portfolio. He owns none of the companies mentioned. The Fool has a disclosure policy.