A two hour brine will not give ya the same effect as a 24 hour brine. Will it help, yes, it depends on how much salt ya got in that brine.
With my brine, I let whole birds go over night about 10 hours on average, but my brine is lower in salt then many.
Like was mentioned, ya can inject bout 10% by wieght if ya gotta rush the process some.
Now some poultry is already injected or "enhanced" an ya can almost get by without brinin, yet it still is able ta add some additional flavour by brinin.
I also wanna add that there will come a time when a piece a meat equalizes out an won't accept anymore. That depends on the meat, the salinity a the brine, time an brinin temp. A good basic brine will do it's job in 8-10 hrs in my humble opinion.