Slitherine

I have this doubt:
a BG tests if receive 1 shoot per 3 bases.
If such as BG has got for instance 8 bases, it means that 2 shoots are enough to test (3+3+2), or maybe that 2 is round up so that we need 3 shoots to test the BG?

For an 8 base BG, you need 3 shooting hits to force a test.

In effect, there is no rounding. For an 8 base BG you need 2.667 hits to obtain 1 hit per 3 bases - so 2 isn't enough but 3 is.