Koffi was doing that because he couldn't to sing new songs before their release, while he had the desire to that, that's why he was always giving some short extrats in concerts. For example in the concerts of 1996 and 1997 he was giving previews of Airways when singing Fouta Djallon, in 2003 and 2004 he was singing Silivi when singing G.B. Gros Bebe, 2005 and 2006 he was singing parts of Plat Favori in Monde Arabe songs.
But in the rehearsals without public at Zenith and later Oshwe 5/5 he was singing those new songs from the beginning to the end, most songs wouldn't be like the way he used to sing before recording it at the studio. Some lyrics he would switch to other songs.