Background : I'm a new-grad junior engineer, recently joined the company around 3 months ago, so still pretty early in my career. I'm currently working on an assigned project which I own and believe it has impact.
Details : My manager recently recommended I take on a quarter-long project in parallel to my current project (as we're short on bandwidth), which I don't feel very passionate about and don't see much impact in it. My understanding is that the work for that project will be on & off while my main focus will still be on my original project
Question : It is good to take on additional responsibility, as long as I have the bandwidth for it, I agree. I'm just not sure if this new project would be beneficial or is the best thing to work on.
How can I handle this situation ? Should I be concerned too much about the project's impact (as opposed to taking more responsibility), especially since I'm still early on in my role / career ?
On the one hand, you'll be able to gain trust from your manager and develop credibility with other stakeholders in your company if the business impact is high like your manager says. This can help with promotion and performance review in the future.
On the other hand, it can be difficult to juggle two projects at a time especially as someone who just started their engineering career. There will be a lot of context switching which will delay the deliverability schedule for both projects.
I would sit down with your manager and weigh the business impact of the two projects. You mention that you believe your current project has a lot of business impact, but the new project may not have as much business impact.
Can you find out why your manager believes the new project has such high business impact? Maybe they have some context that you don't have. At the end of the day, a lot of projects align to increasing revenue for the business, so you'll have to weigh that between the two projects.
You can also express your concerns that the new project might not align with your interests and career trajectory, but one quarter goes by quick, so you could set up an agreement to help out with this project for the next project to be more relevant to your interests afterwards. You just have to be firm with this in the future if they try to keep pushing down projects that don't align with your ultimate goals.
I would also set some expectations with your manager that this new project is going to take away resources from the current project. Ideally, you should wrap up your current project first before moving onto the next project.
Early in your career, your success is dictated more by your ability to complete your work and being a desirable person to work with. The outcome of the project is less important -- you can get promoted even if your work didn't have as much impact as expected. (The exception here is if there's a clear technical failure that led to the missed outcome, then you'd be on the hook.)
Given this, and the fact that it's only a 3 month part-time project, I'd recommend gritting your teeth and taking on the responsibility.
The other nuance here is to unpack why you are "not sure if this new project is the best thing to work on"?
Without clear answers here, I'd just commit to doing the job. The trust you build with your manager will pay dividends later on.
Don't try to overoptimize your time allocation on this one, especially if you think this new project won't deter from your main project. If it does, it's totally valid to bring up options to navigate this with your manager in a 1-1 and jointly problem solve.
From the manager POV, I've always been super grateful to those who stepped up when we were shorthanded. If you feel like your manager is a conscientious person overall, it will benefit you disproportionately in the medium-long term.
Personally, I'm always curious and deliberately try to get exposure to projects that I'm not directly on. It's a very useful muscle to build since I've unlocked many hidden opportunities through surfing other teams' projects in my spare time even at Director+ level.