Accommodation (or "breaking in") of cycling shoes I recently decided to switch to cleats on my technical bike, and I have bought leather mtb shoes.

Based on previous experience with leather trekking shoes, I know that the first 3-4 days (about 40-50 hours) wearing the shoes will feel uncomfortable, until the leather adjusts to the shape of the foot.

So far I have used the shoes for a couple of hours (non-stop) with no complaints, but I would like to have them broken in before a long trip I am going to start in a couple of weeks.

Will wearing the shoes during my daily commute to work (40-50 minutes each way) do the trick, or do I need to wear them non-stop for longer time?
Breaking in shoes is a personal thing.  Some people can wear anything straight away, some people take ages.  I had a set of boots that took over a year to become comfortable but they lasted for a decade.

You don't need to be riding to break them in.   If you can, wear these shoes at work or while sitting down, will help the shoe conform to the foot.  This becomes harder if the cleats are exposed, but MTB shoes are often recessed for increased walkability.

Leather is an interesting choice - if you treat it with beeswax or dubbin then it will become more soft and pliant.   Regular routine application of nugget helps preserve them and maintain water resistance.