Well, it's interesting because my intent for this thread was not about what works for you on the Camino, which IMHO is to go with the culture, but whether or not you adopt this cultural norm after your return home! I am trying to implement the large midday meal AT HOME. I already do it when I am on Camino, more or less!
Under normal "non-Covid" circumstances we live about 2/3 of the year in Canada, and 1/3 in Portugal. We're hoping to eventually be Portuguese residents with occasional visits to connections in Canada, but current family responsibilities--quite apart from not being able to travel at all!--keep us mostly in Canada.
As soon as we go to Portugal, we shift to the emphasis on the bigger mid-day meal for restaurant-going. In small towns like ours, that's why you typically get the best combination of good regional home-cooking and a good deal. Many of the restaurants cook something special, and favoured by the locals, for the menu do dia, and it almost always includes bread, main course with vegies or salad or both, a non-coffee beverage (house wine or small beer or mineral water or flavoured soda), dessert, and a finishing coffee. Often you're given the opportunity to have soup as well. Usually for something between 6.50 and 8 euros or so. And mostly, the places with good cooks are packed--but they almost always can squeeze in one or two more! They typically serve the menu do dia till they run out, so you'll occasionally still see it posted (almost always on a blackboard, except for the fussier places) at 5 or 6 pm.
In Portugal, evening restaurant meals in our household are saved for somewhere special, sometime special. We have one particular restaurant in Barquinha that we like to go to, and their evening, menu-based meals are particularly good, though probably twice as expensive as their menu do dia at lunchtime. I notice that for the locals, lunch out for workers is what everyone expects to do, typically with co-workers. Dinner-time meals out are usually with the whole family, often multi-generational; served late, but not as late as Spain (from about 8:30 on, except when seniors go out--they're often earlier); and generally "a big deal."
For meals cooked at home, we tend to shift between the main-meal-lunch and main-meal-dinner schedules, depending on how we feel and who's cooking or feels like cooking. For much of the year, soups and salads are the stand-bys, other than meals out.
The downside of the main-meal-lunch schedule is that lunch takes a while and you really don't feel like doing anything for an hour or two afterwards. As retirees with control of our own schedules, that's typically not a problem. We just take tasks further into the evening, as the locals do.
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Every time we come back to Canada, we resolve to keep with that schedule. However, North American schedules, which are centred around the 8-4 or 9-5 workday with a brief lunch break, make it challenging if you have to go anywhere and do anything.
I agree that I physically feel better if I eat more earlier in the day, and less in the evening. I'm looking forward to that eventually being my norm!