Mere coincidence?

I have always wondered about the Pallavi’s for Rahman’s songs. They had repeating words in MOST of his hit songs. Is it purely a coincidence or something to do with his style of composing pattern?

Here are some that came on top of my mind:

1. Chinna Chinna Aasai
2. Chikkubukku Chikkubukku
3. Jumbalakka Jumbalakka
4. Chaiyya Chaiyya
5. Nenjinile Nenjinile
6. Azhagina Azhagi
7. Margazhipoove Margazhipoove
8. Narumugaye Narumugaye
9. Malargale Malargale
10. Urvasi Urvasi
11. Hai Re Hai Re
12. Anbe Anbe Kolladhe
13. Anbe Anbe Enai
14. Kaadhal yogi Kaadhal yogi
15. Mukkaala Mukkabala
16. Ennavale Adi Ennavale
17. Thendrale Thendrale Mella Nee pesu
18. Thoda Thoda Malarndhadhenna
19. Anjali Anjali Pushpanjali
20. Sonia Sonia Sokkavaikkum
21. Vennilave Vennilave
22. Theendai Ennai Theendai
23. Nenjil Jil Jil Jil Jil
24. Mudhalvane Vane Vane Mudhalvane
25. Kannum Kannum Kollai
26. Udhaya Udhaya
27. Snehithane Snehithane
28. PachaiNirame Pachainirame
29. Chotta Chotta Ninayudhu
30. Chinna Chinna Mazhaithuligal
31. Kandukondaen Kandukondaen
32. Uyire Uyire Vandhu
33. Vaaji Vaaji Vaaji Sivaji
34. Pennalla Pennalla
35. Oruvan Oruvan Mudhalaali
36. Dippu Dippu Dippu Dippu
37. Thillana Thillaana
38. Sowkiyama Kanne Sowkiyama
39. Suthi Suthi Vandheega
40. Injirengo Injirengo
41. Rasika Rasika Rasika Rasika
42. Thamizha Thamizha
43. Thee Thee Thithikkum Thee
44. Maaro Maaro Chakka Maaro
45. Humma Humma Humma Humma
46. September Maadham September Maadham
47. Thaniye Thannan Thanniye
48. Nadiye Nadiye Kaadhal Nadiye
49. Aiyyo Pathikichu Pathikichu Pathikichu
50. Nenje Nenje Marandhuvidu
51. Maaya Maaya Maaya Ellam Maaya
52. Rukkumani Rukkumani
53. Nagida Nagida Nagida Oh ho
54. Rithu Aaa Gayi Re Rithu Cha Gayi Re
55. Ghanan Ghanan
56. Dilse Re Dilse Re
57. Ya Ye Re Ya Ye Re
58. Tanha Tanha
59. Piya Haji Ali Piya Haji Ali
60. Dheeme Dheeme
61. Kariye Kariye
62. Kuchi Kuchu Rakamma
63. Anbe Vaa En Anbe Vaa
64. Swaasame Swasame
65. Konjam Nilavu Konjam Neruppu
66. Ballelakka Ballelakka
67. Ada Ada Ada Asathudhu
68. No Problem No Problem
69. Paarkaathe Paarkaathe
70. Thee Thee Thee Jagajothi
71. Roja Roja Roja Roja
72. Nannare Nannare Nannare
73. Mustafa Mustafa
74. Velli Malare Velli Malare
75. Sillallava Sillallava Kaadhal Nayakara
76. Mazhai Thuli Mazhai Thuli
77. Kuliruthu Kuliruthu
78. Shakalaka Baby Shakalaka Baby
79. Samba Samba
80. En Kaadhale En Kaadhale
81. Columbus Columbus
82. Smiyayi Smiyayi
83. Oh Maria Oh Maria
84. Kuliruthu Kuliruthu
85. Boom Boom Shakalaka Shakalaka
86. Acham Acham Illai
...
..
.