what is maximum of extending visitor visa?

[huddy]

I am a German citizen and have applied and been granted extensions to my application of a visitor visa 3 times by providing the necessary documents and proof of funds. Each time I asked for a 6 months extension, which has always been approved of.

My questions:
1. Can I ask for a longer extension than 6 months e.g. 8-12 months with my next application?
2. How many times can I reapply considering that I am always able to prove sufficient funds and an invitation from within Canada to stay with friends?

THANKS!!!!