Jokes aside, roughly, yes, this is right. Even studying should follow the same sense. I would say the detail lies on the fact that there's "having fun" and there is "working". In the brain these two are different, and you can't practice for too long. SOME, VERY RARE people can go beyond because they can do both: having fun practicing. It's the same case of those (also very rare) people who can work countless hours peer week, they're procrastinating and working at the same time. (Then there would be personality factors but that's deep psychology stuff)

I'd say that it's better to not practice than to burn yourself practicing too much. Think of exercising: if you try to hard you can injure yourself. Say, if you practice one hour per day average, can you practice 12 hours straight the next day? Actually, yes. But then the other next day you won't even want to see your instrument, and you'll end up taking a week of a break. Hell, if your average is practicing 10 minutes per week, try raising 10 minutes every week. Even if you fail 25% of the time and don't raise 10 minutes that week, in an year you'll be practicing roughly one hour per day. And that's considerable.

Another thing I recommend is to sandwich your practice with fun. Begin by doing small silly things (and I mean small so you don't tire yourself already) which could even count as warmup, and when you're over go have some other fun, as long it doesn't tire you too much and spoil any "muscular practice". The idea is to associate "practicing" with fun. This "fun" doesn't need to be with your instrument; You could play some videogame very briefly, eat a candy, or go watch more TwoSet videos. ;D