That's fine in theory, but you have to find a reasonable deal, find a shop to purchase it in, familiarize yourself with how to charge it up, and all in the time you spend in that country. I've found it burns at least half a day - usually not worth it. Most of my leisure travelling is motorbike touring, and I may spend each night in a different country, or cross borders several times a day (mountains with interesting roads are frequently on borders).

If my travel was simpler, sure, it's somewhat workable, and I do have e.g. a German SIM. But it's usually better to just rely on hotel wifi, cached maps on phones, offline GPS on bikes, etc.