Why tuesday and friday....????

Question

hi,some of you must be knowing about the serial blasts in jaipur,india.......so i was thinking that the blasts took place on 13th may tuesday....many such incidents take place either on tuesday or friday and on 13th,even the mumbai blasts took place on friday......

so dont you think that on these days there should be strict checking everywhere in the country......?????

what do you people think about it...????