Make sure you have 3 to 6 months of expense in savings first before we talk about insurance.
Dreamer
Most singles don't really have much savings, so you're not the only one my friend.
As to the opinion of buying as little insurance, that is a Highly Personal Decision and definitely NOT any rule of thumb.
Cause at the end of the day, if something unforeseen were to befall you, and you bought as little insurance as you could, who will suffer? You or the person who told you to buy as little as possible. Will he be willing to give you the money to pay for your expenses or will it be the insurance company?
If I were to offer you Free Insurance, would you want to have as much insurance as possible? Definitely, right? But the fact is Insurance is also a business, and we do not ask you to pay exorbitant amounts of money and then give you peanuts coverage. Instead, we take only a fraction and give you a greater amount of coverage than you yourself normally wouldn't be able to afford or have.
All I'm saying here is to purchase based on what You yourself feel that You Need and can Afford. Who is to say that it is wrong to spend 10-15% of your salary on insurance? As long as you feel you want it and can afford it. Some people whom do not believe would probably tell you that, on the other hand some whom have seen the great benefits of it would tell you otherwise.
When you yourself feel that whatever you have is good enough for you, then you can have peace of mind and not worry about the consequences of an unforseen situation. There's also a fine line between what You Want and what you Need. You might want that BMW but do you actually need it? But you insist on getting it because it is what you want.
Situations does change over time, and yes you can upgrade it or purchase a new policy. That is why a good agent will help you realise that and explain to you the details to make sure you understand, they will service you for life and be a lifelong friend.