Dear Ideal Singh Jee,

From Guru Nanak to Guru Gobind Singh Jee, it is one process of evolution. All put together is Sikhism and its philosophy. Any attempt to segment it according to the teaching of each guru is to negate it. As our limbs or other organs (teaching of each of our guru separatly) separated from our body (sikhism) have no real meaning, in the same way considering each guru separately also does not give you the grasp of the totality; it does not help the cause of sikh religion.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/sikh-sikhi-sikhism/41-teachings-guru-nanak-dev-ji-guru.html

With Love and Respect for all.

Amarpal