That is true... Perhaps if you do it once a day you'll get better chances... Usually the sperms live for about 3-5days in your body...I would say - better a big blast than tiny little blasts

It takes 24-48 hours for sperm to develop.
If you are trying to conceive the best thing to do is have sex every other day during your high fertile window.

For a typical 28 day cycle, with ovulation occuring approx day 14 (day 1 being the first day of bleeding) the high fertile window is days 9 to 16.

Sperm can survive upto 5 days in the fertile female body and an egg is viable for approx 36 hours after ovulation, so the high fertile window is from 5 days before ovulation until 2 days after - 9 thru 16