Its not so much sweeping your partner that the first tactic has a flaw with. Its in diagram 3, the red unit has to move out exposing his back to unknown area with no cover, before blue unit can get his sweep in.
"The hydrogen economy car from the people who brought you the 'Hindenburg
'" - Glen Foster
Condoms do not guarantee safe sex any more. A friend of mine wore one and was shot by the woman's husband!