Tart and gravel flat roof repair

Hi Leo,

I have a tar and gravel roof flat roof. It’s having water leaks in a few places due to water ponding issue. I have read that there are products such as Roofslope to create proper slope or Elastek 505 puddle plaster to create slope. Does these work? If not, what product do you recomend?. If I use roof cement such as Roof-x-tender would it cracks if it is too thick? Please let me know. Thank you for your time.