As your income increases, you should consider increasing your disability income insurance coverage because you would have to replace a higher amount of income to keep pace with the higher standard of living to which you and your family have become accustomed. When you buy individual coverage, it sometimes makes sense to pay extra for something called a Future Purchase Option rider. This provision ensures that health issues that may have arisen since you purchased your policy won't prevent you from increasing your coverage.
You'll also want to consider buying individual disability income insurance (or increasing existing coverage) every time you assume a significant amount of new debt. The bills won't stop just because you've been in an accident and are unable to work for a period of time. So you'll need a source of replacement income to make sure that you'll still be able to make your mortgage or car loan payments.