About business

Now I'm 30 years old and working as a IT Engineer. I have switched jobs 3 times up until now. The number is large at my age, in Japan.
Even today, some people like lifetime employment system. Earlier generations think long-term employees is reliable, but if not, they think there is something wrong with people who change jobs.
I understand that long-term employees is reliable and valuable to a company. But on the other hand, spending too much time in one spot encourage someone to be lazy. It's not necessary to learn new things, I think it is far more dreadful to be bore.
However, I'm not young enough anymore. Is it a time to reflect on my career? That's a pain.