So i'm not good at HRG yet and I need to practice more, but in the meantime I wanted to atleast finish my first run cause i'm new. So I wanted to know how much time does not doing HRG in pre cha. 3 cost? And also another question, how long would a near perfect beginners route run be 5 hrs? Thanks!

HRG is hazard respawn glitch. You can check the glitch index if you don't know what it is http://www.speedrun.com/ttyd/guide/gd37h#ch40Hazard_Respawn_Glitch

If you don't trigger chapter 6 before entering chapter 3, it would waste around 4.5 mins. Route would be the same (in terms of the fights), you just need to go get the yoshi egg the normal way. (this used to be how we did it before HRG).

And I don't understand your second question.

oh just got it, the WR before TRE/PS was 5:10. So that I guess.

@Vynneve Hey thanks! I really appreciate it. I am currently working on bookcase jump and practicing cha 3 pt 1 at the moment. Hopefully I can get HRG down. Thanks!