Almost all the "hits" have very limited words insterspersed with high dose of beats,flute pieces and weird voice modulations. And mind you, those limited words are repeated until you catch them, like
aaja aaja in jhalak
jane jaan in aap ki kashish
ashiq banaya in ABA...
lagan in lagan lagi...
Tera in tera suroor..
tera in "naam hai tera"...
every line in ashiqana hai dil is repeated 5 times..
jana in tu yaad na aaye aisa koi din nahin
sayoni in "I love you sayoni"
As far as I can understand, this kind of phenomenon happens when you already have a tune ( "have a tune" as in lifted ) and try to fit the lyrics on it. It may be his style to emphasize on a catch phrase, but seems unlikely given his "hook or crook" methods shown on saregamapa.
A singer with "very" limited range and "unconventional" voice has actually used someone else to do some alaaps/saregama in his songs and difference is noticable.
This would also explain his fixation on 20-20, he was planning to express his opinion for a long time, he has a big thought ( tune) while he just could not fit words so kept repeating 20-20-20 and 20 with beats on table.