I understand your confusion when it comes to finding a lamp that fits your situation.
To keep it simple, plants won't care about wattage, lumens, or how much light is produced in total. The only thing they care about is how much light is landing on their leaves.
We have made detailed maps that show how our Z5 LED grow light performs at three different heights in one side of a 24x48" reflective space:
And by mirroring the results and adding them, we see how two Z5 lamps perform together:
When it comes to tent size and limitations, it depends on your goals, the number of plants, and their size. Growing one medium-sized plant in the center of your tent will require less light than if you're growing several large plants and fill your tent.
Our Z5 LED grow light produces around 900 PPFD in the center, when hung 12
above the plant canopy. This is fairly close to the upper limit of what adult cannabis plants are comfortable with receiving during flowering. between lamp and plant should be accounted for when your plants have more or less finished growing/stretching. Giving your plants more light than this can cause light-stress and bleached tips.
In other words, 10-12