How many reps of something do you need before you can use the term 'streak'? It's definitely not one, two doesn't feel like enough.
Accumulation of a streak is a key tool in language learning apps, but the defence of that streak can become the stronger motivator than actually wanting to learn a language so you might lazily complete a rudimentary lesson just to keep it alive. They also let you 'repair' a streak in exchange for money which provides zero learning experience and makes the streak much less credible.
This is day 67 of daily writing; definitely a streak. I have been cycling two weekends in a row. Would deciding this is now a streak help motivate me to ride again next weekend or is it an absolutely pointless metric?