Is adding amendments really important?

i was wondering if its better to plant a lot of plants in native soil and just add dolomite lime and ferts....or is it better to add some amendments(potting soil, compost,etc.) and only plant a few? in other words is it worth it to haul store bought soil all the way to the grow site, or just plant more plants?

well?..............

Haul in soil and mulch and plant fewer.
This year i put out 50 or so clones in a mountain grow and did not amment the soil.
Though, they got regular water and organic nutrient teas, only about a third of them reached 4 feet tall. They should be trees, but many are not going yield an ounce. Anyway next year I will plant fewer in ammended soil and expect better results.

thanks for the advice

it also really helps to cultivate the soil and mix amendment down in.. makes room for roots to spread out..