A month ago we adopted a Lurcher X Border Collie puppy. She is 4 months now and I'm struggling to understand if she is a very high energy puppy or just overly tired. My husband walks her for 30 minutes in the morning in the park, where she likes to play tug of war... during the day I do some basic training with heralong with some puzzles and in the evening she goes on another 30 minutes walk, this time with me. Needless to say that half way through the walk she starts doing what lurchers do best... she runs like the wind and does not stop for anything, eating leaves, grass, sticks, stones, jumping, biting, barking... (i use a 10m lead for this purpose) and when we get home, she starts the whole process again of running, etc in our backyard. Am I overdoing it with her? I tried doing less exercise but she just whines all the time and I'm lost on what to do because I've never had a dog like her :/
What you have is a high energy dog. She needs lots of physical and mental stimulation to be happy.
The running around and whining if you don't offer enough training are good indicators that she has more than eough energy. If she were tired, she would be reluctant to go on a walk and would walk slowly instead of running around.
Maybe you got confused by her yawning a lot? A tired dog yawns mostly quiet, sometimes accompaied by some rumbling and mumbling. If she yawns excessively loud, maybe even with a whine, it's her way of communicating that she's confused or insecure what to do in a given situation. That can happen during training or in any situation she's not used to.
In general your schedule of 2 walks with short trainings and puzzles in between looks like a very good solution for this dog. If she loves training because she's basking in your attention, make it a habit of teaching her small tricks and then ask her to do a trick every time the opportunity arises. You can even do it during a walk to strengthen the bond between you. That has the added benefit of depleting more of her excess energy than a walk alone would do.
Another way to entertain her are food toys like puzzle feeders, food dispenser balls, Kong toys and even play fetch with a prey dummy filled with treats. Most of them require little of your time to prepare but entertain your dog for a while and offer some excitement. You can even feed her her entire meal in a puzzle feeder.
If you need some inspiration for different games and puzzles for your dog, please look at this compilation.