Does the halogenation of an alkane also produce haloalkanes of a longer chain length?

Take a typical halogenation of an alkane reaction (the bromination of methane).


$$\ce{Br\_2->Br· + Br· (in the presence of UV light)} $$


$$\ce{Br· + CH4->·CH3 + HBr} $$


One of the possible termination reactions is


$$\ce{·CH3 + ·CH3->C2H6} $$


Since there are still bromine radicals present, does this newly formed ethane then undergo this reaction?


$$\ce{Br· + C2H6->·C2H5 + HBr} $$


What's to stop this new ethyl radical from continuing this process again? Wouldn't the bromination of methane form secondary products of bromoethane and propane and so on?
How do you ensure, when synthesising a haloalkane through this method, that you only form the haloalkane of the specific chain length you need?


Am I missing something obvious?


