My observation is that both occur and the balance tends to vary by company. I've been in the room when technology N+1 was selected because there weren't many de

My observation is that both occur and the balance tends to vary by company. I've been in the room when technology N+1 was selected because there weren't many developers for technology N, but I've also seen developers working cool and trendy things into projects that don't strictly need it (where there is a sliding Overton Window around what is "cool" or "trendy").