YES! In fact it's far easier to get high GPW values with smaller plants!
Sea Of Green = SOG. Plants that are run in high # counts, close together.....Some do bigger plants, most do small plants.
Most yield estimates are taken from the total yield of plants bloomed at 8 inch's tall (or smaller), filling in a square meter space.
Look at Dr. Greenthumbs seed site. He does it that way and lists it as such.
Then you have rotating gardens that will exemplify SOG perfectly.
Now imagine that, set out in a flat ebb system tray.
What you see above is a near perfect example of what I did with a 2X2 ebb tray. Same for the 64 plants in 6 inch diameter pots in the tent (I look back at that now and wonder why I didn't use square pots. To be honest.)
Strains used are a key ingredient to this success.
In the end. I find it far more productive from a quality standpoint. To grow large plants and go for potentials. Yield is nice but, quality equals higher value.
Your 1.5 - 1.7 per watt - Is respectable to say the least. Now add superior quality to that, and your winning the game!