Helping when needed is great and an important part of the job, but helping train people to do things more efficiently is the bigger goal.
My instinct is to be the super busser and clear everything all the time while touching tables. I'm good at this. What I need to be better about is correcting a server when they drop something off at a table but don't prebus while they're there. Of course I could swoop in and clear everything myself but they shouldn't be leaving that table empty handed if there is ANYTHING they could take. Some servers are good about this, some aren't. You need to find who is struggling with this and help them get into the habit.
This is unfortunately where managers can get a lot of hate. Y'know, the old "my manager is so lazy he told me to go do this when he could've just as easily done it himself" stuff. And believe me, there are managers who take this and run with it, refusing to even clean up their own messes, but it's not all bad. A big part of the job is training staff to be more efficient rather than just picking up the slack yourself.
When I'm actively helping on the floor I try to stick to busser things rather than server things. I don't want to step on anyone's toes but at the same time I'm not going to refuse a request just because I'm not their server. I can make pretty quick laps of the floor and my usual strategy is that if I come across a table without drinks/coasters/some indication that a server has been with them I will ask if they've been helped the first time and tell them that their server will be right with them. If I make a second pass and they still haven't been helped then I'm taking their drink order and getting them anything else they need.
The same is true for cashing out. I know it's kind of a last chance to get in some facetime but if we're on a wait and I need to turn tables I will give them until the second pass but if their card is still waiting to be run I will run it.
Something that a lot of servers don't seem to get is that I'm doing everything I can to help them. If I have to take your table's drink order or cash them out then you better believe I'm talking you up and making it very clear that they're not being neglected. I want us ALL to look good and I want the customers to be happy. I want them to give you a fat tip and I want them to come back.
Don't be afraid to take input from anyone and don't let that feel like it's undermining your authority. A good manager is one who can recognize and implement a good idea, even if it's not their own.
Most importantly, have your people's backs. I know that your hands might be tied by corporate, the owners, other managers, etc. But whenever you can, be the manager your servers will want to post about here, singing your praises. The worst thing is when servers are told they must adhere to a certain policy but then as soon as a customer questions it the manager just waves their hand and the policy disappears. That's the shittiest thing you can do. It makes servers look stupid and incompetent and encourages the career complainers to question anything they don't like.