Yesterday I had another lesson with Victoria and one of the concept we discussed was parallel fifths and octaves in tonal and polyphonic music.
You see, between the Renaissance and Romanticism (ca. 1400-1900), composers wrote music which required independence of voices.
Parallel perfect intervals, such as unisons, fifths and octaves would diminish independence of voices. Therefore they were not really allowed in such music.
So it's best to move the bass in the contrary direction with soprano. Or keep the common notes of two chords stationary, if you like.
This solves all forbidden interval problems.
Hope this helps.
By the way, Vidas told me that the first students started to respond to Vidas Live Coaching and he's got already many questions lined up for the 1st session. This program starts in two days on Thursday. The best part - for Total Organist students - it's free of charge. So if you want to talk to Vidas personally about your struggles in any area of organ playing, don't miss it.