"do a good job" vs "did a good job" vs "have done a good job

[rrock]

Dear friends:
Are these sentences below correct or usual?
1 You did a good job.
2.You do a good job.
3.I've learned something
4.I learn so much.

Thank you for your help. you're the best.

[Josef]

They are all correct and normal.

1. You did a good job. << past simple tense
2. You do a good job. << present simple tense
3. I've learned something. << present perfect tense
4. I learn so much. << present simple tense

No. 2 is present simple tense which indicates a generality. It is more likely to be heard as "He does a good job", but "You do a good job" is certainly correct and possible.

Why don't you get XYZ to fix your car? They do a good job.

Last time my car needed servicing I took it to XYZ. They did a good job.

You should try to get a contract with the council. After all, you do a good job. I'm sure they'd be delighted to give you a contract.