Exclusive distributor or several distributors in Mexico: what has worked for you?

Many companies coming to Mexico ask this before their first contract: give one distributor exclusivity for the whole country, or work with several distributors in Mexico, split by region or channel?

I would like to collect the experience of the network:

• When did an exclusive distributor work well, and when did it hold you back?
• How did you split the country: by region, by channel or by product line?
• What did you put in the contract to protect yourself: sales targets, duration, an exit clause?
• How did you find and vet the distributor in the first place?

Real cases are the most useful, from established brands and startups alike, without naming clients. Answers in English or Spanish are welcome.