Differences between using “used to” and the simple past

Question

In following examples I understand:

1. Situations are in the past.
2. Situations are continued until some time and stopped.
3. Situations are regular, routine and repetitive.

My question is should we use used to or simply use the simple past of a verb? When and how do we use used to and what are the differences?

Please, explain this to me with examples.

E.g. 1

I used to prepare this report when I was in Company X.

I prepared this report on daily basis when I was in Company X.

E.g. 2

I used to work for this company.

I worked for this company for 8 years.

E.g. 3

He used to play for X Country.

He played for X Country.

E.g. 4

He came to meet me regularly.

He used to come to meet me regularly.