If you’re trading a demo account or a small account that means little to you, then yes, 25%, 100% or even more is possible, it’s certainly not maintainable though. Don’t under estimate the discipline of physiology, with a bigger account even the ‘norm’ becomes magnified on an emotional level.
25% a month is a wonderful thought and nice to ponder upon whilst travelling to your usual day job each morning, but it’s not reality
Personally, I usually risk 3% of my account balance on a single trade and struggle to maintain an average of over 8% per month. But, i’m a wired gambler and always have been.
I had one experience last week where I went to a Roulette table. Starting with $200 i was betting $50 on a spin with no care in world. When I grew this to $15k in the same session I was unable to put down $3.75k [the same 25% risk as when I had $200] on a single spin; not because I wasn’t allowed,but because emotionally I couldn’t handle it.
Sure Roulette is not the same as trading, but my god, when the money gets big the emotions will kick in.
Edit: FYI: The end story was that I walked away with $0 after the end of the night… $15k to $0 - the next morning I was furious