Be careful about constantly taking on responsibilities that aren't part of your job. Once everyone gets used to you doing them, they will stop seeing them as extra and you'll be sc--wed. I'm talking from experience.
3 replies (most recent on top)
If you got a job offer, you could use the extra responsibility to demand more money or else you are going to walk out the door. But why would you take the counter offer, when you could just start working for a better company?
And also be sure that you are reassigning or de-prioritizing equivalent current work to maintain balance.
This is sound advise. I learned this the hard way. If you do take on extra, make sure it's strategic and will be useful for your long-term career goals and work-life balance.