HR is one of those departments that can either be an incredible help to the manager or it can be the biggest impediment to the manager. Part of that is the way HR views their role in the company. Part of it is how the manager works with HR.
HR departments generally fall into one of two categories.
Intent on making and enforcing rules and procedures designed to protect the company from liability. (Impede managers)
Intent on being a resource to create the best employee experience possible while also meeting the legal needs of the company. (Helps managers)
Best case scenario for a manager is #2. NOTE: HR departments that fall into category #1 feel like they are helpful, they do not see themselves as an impediment - which is why they act like they do.
Regardless of the category, a huge mistake managers make is to offload too much responsibility to HR. Managers think they are the expert and ask for help when needed, but are way too hands off.
The best example of this is hiring. When a manager needs to hire someone, they ask HR to put out an ad and get the candidates. In many cases, HR is working with a bad description of the position (and little understanding of what the manager is looking for), which makes doing their job successfully almost impossible. Then, HR will filter through the candidates and send over several for the manager to review. As you might have guessed, because they don't know what the manager is looking for, the candidates they send over are probably not the best. Then HR will do a phone screen and set up interviews for those they consider a possible match.
Let me be clear - this isn't HR's fault. The manager needs to demand that they are a bigger part of the process. It is more work for the manager, but it is important to make the right hiring decision. The manager needs to fully think through what characteristics and skills you need from the candidate, communicate that clearly to HR, review the candidates (all the resumes, not just the ones that HR filters out to you), and tell HR what to ask and look for in the phone screens.
HR is a great resource to help you do these things and offer their expertise, but do not simply outsource it to them.
Think about all the ways you work with HR - are you working with them or simply interacting? You can't be great unless you work with them.