If u see one of the pics, it states that the intervals are given till 40,000kms after which you are to keep following the same intervals. 40,000kms is a LOT, and major parts changed every 40,000kms is not a big deal. Also, I've driven mine around 83000kms now and the belts are in great shape, they don't need replacement yet. Inspection is the key
Regarding plugs, if u were to inspect your plugs at 10k, I don't think you'd have the heart to continue using them further
I used iridiums for a long while, and they do last, but I've since realized that nothing beats copper in performance. The life of copper ones is short, but if u compare, coppers changed quickly cost around the same as iridiums changed after a long time.
As a general rule, quick replacements of standard parts is better than expensive parts not needing replacement for a while. In Pakistan's environment of excessive dust and bad fuel, copper spark plugs changed quickly are better than the same iridiums for a long time. Similarly, a mineral oil changed quickly at 2000-3000kms is far better than a synthetic oil used for 7000-10000kms.
The same goes for air filters.
Regarding oil, 0w20 is just recommended. Since 80% of this manual is the same as foreign ones, its understandable. In quite a few climates, 0w20 would be ideal.
They have given a chart to help u unferstand and choose the best oil for your car. For Pakistan, 10w40 and 20w50 are ideal. This is also stated at the back of the manual, written specially by PakSuzuki. I personally prefer 10w40 owing to lower viscosity that is ideal for cold starts (the oil circulates quicker than one with a higher viscosity). The major chunk of engine wear occurs at cold starts i.e when the engine is started every morning or after the engine has cooled down completely, so you need to keep that in mind.
I'm attaching a pic of PakSuzuki's oil recommendations.
Sent from my GT-I9300