Also known as the trading model's shelf-life. Based on what I have heard and learned, the average active trading model has a useful life of around 18 months. After that the rest of the market has adjusted and its edge is gone.

If rumours are to be believed, several "slow" hedge funds have models that remain useful and profitable for 5 years or more. Then again, those models are not used to conduct exchange trades but rely more on aspects of fundamental analysis.

Rather curiously some of the largest banks and tech-heavy asset managers tend to sponsor meetups and events like PyData - every now and then doing a slot on some of their open-sourced stuff. You might see a talk on 5-year-old trading model internals with large chunks of it opened up, or they could present some of the internal UI or visualisation libraries. The latter tend to be things that they no longer actively develop (they're "ready") but maintain for their ongoing persistent needs.

Of course anything that actually brings them money and/or gives an edge is not even discussed.