"If you ever do extended survival training, you'll find that it takes a lot of work to get food by finding it here and there throughout the year. Plus, it is not assured that you'll find enough in any one place."
If you're ever reduced to really extended survival training, of the sort where nobody is going to come and rescue you, ever, you'll find that it does not take all that much work to get food by finding it here and there for about 9 months of the year. Roll over stones and turn over logs: there are plenty of insects and worms and all sorts of nasty protein sources which can be eaten, and which will keep you alive. Most green stuff can be eaten, but most of it is not really necessary. Bugs and worms will keep you alive, and they are plentiful just about everywhere. And horrible.
During snowy periods...well...there's a reason naked mankind didn't develop in the temperate and subarctic zones!
For that, you have to live off all that stored bug fat, and store up acorns (which are horrible, but edible). The inside of pine bark will keep you from getting scurvy (and is also horrible).
Life as a wild man is short, but it's not really starvation that gets you. There really are enough bugs out there to keep you alive indefinitely. The problem is that the combination of cold and exposure lowers your immunity, and you die of illnesses and infections much more quickly. A cold becomes the flu becomes pneumonia, and pfffft, you're worm meat.
In fact a fair number of buglies are considered special treats and are not all that different from eating shrims, crawdads, calmari and the like.
White Oak acorns are sweet, and in North America there are also Beech nuts, black walnuts, butternuts etc..
Generally gatherers spend less time on survival than farmers.