Generally companies report earnings quarterly as well as yearly. Earnings are typically calculated using many assumptions. Another financial report is the cash flow statement. This is often more important than the income statement as this is what investors generally are most concerned with. To see why, let's look at depreciation.
Depreciation is a non-cash expense.
Firms that attempt to maximize earnings will lower their depreciation. This will cause taxes to increase which will cause cash flow available to shareholders to decrease. Thus, profit maximization is not a worthy goal for a manager whose intent is to maximize shareholder value. Although highly correlated with profit, a firm's cash flow statement is less open to assumptions than is their income statement. Reviewing financial statements can be quite time-consuming.