Do lawyers need given instructions or do you trust their judgement?

[OhioOhioOhio]

Just that. My friend and I disagree about how he should approach his divorce.

Yes, they need instructions. Usually there's a range of options available to their client so a lawyer should explain the pros and cons of each one to help the client decide what's best for them.

They should take instructions, based on having explained the options to their client and the pros/cons of each.

Yes, as above. It is important they explain the options and possible outcomes/consequences so the client can make informed decisions. But once the course of action is decided, the lawyer should not need step by step instructions.

The Law Society has lots of straightforward information on its website including guides to dealing with common legal issues.This is the link to its guide to divorce
[https://www.lawsociety.org.uk/for-the-public/common-legal-issues/getting-a-divorce/]

We need 'instructions' i.e. confirmation of your decision on what you want us to do once we have explained the options. In my field the good lawyers will explain your options and then tell you which we would recommend you go with and why, but ultimately we will act according to your instructions. If we think you have made the wrong decision you will probably be able to tell anyway because we'll confirm in writing that a different option was recommended and discussed but you decided to go with a different choice.

I'm a solicitor and decisions are definitely for the client - it's my job to inform them of options, make recommendations and then (so long as there isn't a legal or ethical problem) work to achieve what they want. That all involves an exercise of judgment but I don't substitute my judgment for that of the client - to do that I'd need to have been granted power of attorney!