Some with headphones, but PanGirl (stereo field) always with speakers.

Both

If you can, make the majority of your practice on speakers but headphones should still be fine if that's all that's available to you

Did SG with headphones for a while and it's a lot of fun, but when I finally decide to tune my room and get some decent speakers, I had to go back 10 levels on every modules and struggle from there. So I would not recommend it unless you have hi-end calibrated headphones and you entend to work with it as your primary tool.

Both

Thanks, good to know! I'm just making music for fun, so I didn't invest much into the acoustic of my room, just the bare minimum. I'll try to use both to practice on soudgym.

Speakers only. what am I missing? What is the benefit for headphones. not being snarky. honest question.

Speakers excite the room and produce 'room frequencies' that hit your ears. If you mix to the room, it might not sound good in a different room. Headphones give you an isolation, but if you only mix to headphones, it might not sound good in a room when people are listening to the track. So testing a mix should happen in headphones, and then in several rooms on several kinds of speaker if you can, then try to average the performance.

Tha'ts good to know, thank you

My case is that I'm using only headphones, I can get a good ear training anyways. I see the improvement of my detail recognition, so I think it's not that important what you use, but what's more important is how you use it.