As a freelancer I feel I should try to commit for at least a year - and I will try to work a bit longer of possible. I believe this looks better on my resume as well.

I think it's hard for most jobs, at least in my space (mobile software) to do much effective work when staying only for -let's say- 3 months at some company.

But mismanagement happens. The example you mention of being let go after just 3 months should be the exception, not the rule. I certainly never experienced something like that. Then again I like to work for big clients, feels to me more guaranteed they will still be in business tomorrow and me getting paid.