When you’re laid off Group employer disability programs wouldn’t apply. There may be some that have some level of portability but that is extremely rare. As in litteadv’s answer, employer plans really insure the payroll they’re really “income protection” more than they’re “disability” insurance. Depending on your employer the limits, waiting period, and definitions of income may be different, some may not cover bonus income, etc.
Your IDI policy would likely pay if you were laid off. IDI typically has a stated benefit, $1,500 per month as an example, that would be set based on your income at the time you buy the policy. The policy may or may not offset for other benefits you may be entitled to, state disability, employer disability, etc. You’d really need to check your policy terms. But, typically, IDI pays the stated benefit amount as long as you meet the definition of disability written in the policy regardless of your employment or income at the time of disability.
Some companies will cover or make IDI available to employees on a discounted and/or reduced underwriting basis. Employer sponsored IDI is generally portable after you leave your employer. If you are offered IDI it is typically worth buying. The underwriting of IDI is generally very stringent if you’re buying as an individual. It’s generally difficult and you generally need a very large income to cobble together a lot of IDI coverage, so buying it when it’s available is generally a good idea.
Your auto insurance policy may cover some very temporary loss of income. But it would really only be intended to cover some small cost of living required for a hospital stay or something similar, not to be relied upon for a protracted disability.