A quick survey of the classical guitar pedagogy/method books that I have at home all agree that full planting should be developed first. In fact, Anthony Glise's book, Classical Guitar Pedagoy
and Larry McDonald's book, Conservatory Tutor For Guitar, Vol. 2
both discuss the use of individual finger planting as a pre-full plant skill.
The individual finger planting starts with each right hand finger on a string, as in a p-i-m-a-
pattern. Only one finger plays at a time, while the others rest on the strings. Each finger returns to its string after playing. It creates a staccato type of articulation. This exercise helps to develop finger independence and control but isn't often used as an actual playing technique. Both of the above noted texts recommend starting with the individual finger plant skills and then move into full planting and sequential planting skills.
ps. I am assuming that sequential planting is more about learning technique as opposed to something that is often useful in performing a piece of music on a classical guitar. Am I right about that?
The sequential plant is
a valid right hand skill. I was fortunate. My primary guitar teacher taught me both full and sequential planting early in my training so their use in my playing is very natural. The sequential planting is especially tough to learn though.
Since you write that you have not learned either full or sequential planting, that leads me to understand that you play arpeggios without preparation. This is actually much harder to do as the fingers can lose reference to the strings causing difficulties with accuracy and tone control. You might be pleasantly surprised with your playing once you do some solid work learning to play using full and sequential plants. The Guiliani exercises are great. You could also use some easy arpeggio etudes if you want to play something more musical.
So much music, so little time.