Stimulants are different for everyone. I have never had more energy than 45 minutes after an EC stack (Bronchaid and caffeine tab). For most stimulants I develop incredible tolerance and quickly but not with this, but again everyone is very different with stimulants.
I get focused and I can use that energy how ever I choose from weights, cardio, or even in the bedroom. Generally considered safe if cycled, but as always do your own research about what you put in your body.
A bit more dangerous in IMHO but some add Yohimbe to the above stack and claim it works even better. I get a bit shaky and nauseous by doing so and just feel funny with the Yohimbe so I leave it out.
For me EC is still the gold standard by which all others are compared for an energy and fat loss/muscle sparring combo. Some use every 4 hours 4 times per day but I can only use it twice with last dose no later than 2-4 if I want to get to get to sleep. You may even want to cut in half first time you try.