I depends the beans and their freshness. If soaked and not 2yo+, it’s less than 1 hour for most of them. 30 min is enough for azuki and chickpeas if soaked 48h.

There’s other tricks: various beans can be found in the form of instant powder or flaskes (1 min watering - no cooking) semolina (5 min watering - no cooking) and pre steamed (no watering - 10/20 min cooking). I bring those to hike on the mountain and use gaz only to make them hot. Mixed with cereals semolina, spices, herbs and oil/nuts its the perfect submit meal.