Question: Palms, Cacti and others with 3-1-2
We read on this forum that most if not all plants require or use nutrients in the 3-1-2 ratio. In my experience, pretty much all my "traditional" potted plants (houseplants, camellias, azaleas, gardenias etc), as well as plants in the ground, thrive with this ratio, so I'm not disputing it.
However -- I am curious about when reputable sources, like the Sunset Western book, say that certain families of plants should be fed with different ratios, like palms for example with 1-2-2.
Is it best practice among this group to stick with the 3-1-2 for everything no matter what -or- do we deviate a bit to accommodate special groups like low nitrogen palms/cacti/succulents or whatever might be suggested from other established sources?
Which path is optimal for these certain plant groups in which 3-1-2 is not suggested outside this forum?