Debraj, please can you break down the formula as i'm not sure what its doing:
=TEXT(CONVERT(SUMPRODUCT(LOOKUP(ROW(INDIRECT(CONVERT(B2,"day","mn")&":"&CONVERT(C2,"day","mn")-1)),$I$2:$I$6,$K$2:$K$6)),"mn","day"),"[hh]:mm:ss")
Any help in handling weekday and weekends?
I failed to mention...