Everything depends on what type of led design, optics, efficiency, ppe, ppfd, Spd (spectrum), ect... you're using. Environment is key. But what is "Full Spectrum"? Pretty sure it's not "Full Spectrum". Many burple manufacturers call their light Full Spectrum as do many white manufacturers of led so called grow lights. Be careful what you believe because neither is full spectrum. It actually takes the right ratios & combination of both to produce a full spectrum light & even then, thats only in the visible frequencies,not anything similar to the Electromagnetic spectrum of the sun.
A combination of whites & properly tuned monochromatic diodes allows one a Horticultural spectrum that is broad, yet targeted from 365nm-780/800nm ideally.
Veg+Bloom mode on burples are usually best always being used together as one is typically blue & the other red. Alone both are lacking but together they will work better. Just dim or raise your light for veg to wipe the hight that you use in flower. If burple, a few white led flood lights around it (K-Temp depending on existing spd) will help dramatically.
Old thread but still applies to several using budget lights.