Why do risky companies tend to have lower target payout ratios and more gradual adjustment rates?

Because risky firms has high debt which it has to repay in the future, when it has high debt it need cash to repay the debt. So, it prefer to lower its target payout ratio. Furthermore, pay lower dividend will reduce the debt ratio of the company( By doing this, firm can lower its default risk). After it repay the debt, it will gradual adjust the payout rate to the higher payout ratio.