By different oils I assume you mean the engine oil and the differential oil, there are only the two, ( brake fluid to be changed also, it has an oil content also). My take on it is, I have been servicing all vehicles since '87 and at that time a mineral oil was the norm and generally was changed at 3000 miles, it would break down much easier than today's semi/full synth oils. As time and technology moved on we got tighter tolerances and emission in engines and semi synth oil totally replaced mineral oils, the service intervals increased to 5000miles +.Then fancy fuel injection systems came along and required the engine oil to preform extra functions like create hydraulic pressure for common rail units etc and an even higher spec oil was called for, this and ever increasing service intervals, had a full synth oil introduced.
Our CT intervals for engine oil is 8000miles and this is in part to the high quality oil available today and in part to competition saying their intervals are longer and buyers thinking it will cost them less over 6 years of ownership to buy that brand of bike. I like to stick to around 5000 miles intervals or if its close and I am going away on a 2000 mile trip, I will change it for peace of mind.
With relation to the Differential oil, It does'nt need to be changed as often but it has done the same mileage as the engine oil and at 200 mls quantity ( a litre can will do 5 changes)and about 10 minutes to change its a no brainer for me. A side note to this, at my 8000 mile dealer service the air filter was changed ( it was'nt to be changed until 24k miles!)as it was filthy so its always better to check and be safe!