Pls let me know if its RTA or IGT and how its timed. For example on challenges there are no rules

RTA is more for full-game runs such as career, season and training. On individual levels, the IGT is shown upon finishing the stage, whereas on training courses, the best time is on the left side of your screen. There's also explanation under the "Game Rules" tab.

As for challenges specifically, it's difficult to have one common ruleset, as the objectives vary. If you want to submit the run for full-game leaderboard, then it probably requires you to complete every challenge, in which case RTA would be the option. If the challenges get added into the individual level leaderboard, then you could use the challenge specific IGT.

Hi, Rave_SR, how are you?
I'll fix the rules and I'm apologize for the omission, but as Shad4w says, Full Game categories uses RTA. ILs uses IGT, as the game provides an accurate timing.