Planning formula average speed to get good useable footage.

[Rorysee]

My Autel Evo drone arrived today. Just trying to work out a rough estimate for time, distance, speed and battery life for a flight so I won’t run into trouble.
So roughly speaking 1 km @ 8 km/h = 8 min, descent slow speed. and 1 km @ 30 km/h = 2 min, half the Autel evo drone speed. If I work on these rough parameters I should be fine. Or have I got it wrong?
I need a rough headspace ratio that I can use quickly and comfortably fly and land and have decent footage.
For example, I rendered a clip in google studio working on the above rough formula and the footage is sped up in google studio to 40 seconds roundabout.

 

[Rorysee]

so laminated this and put it in my EVO Bag gives me a rough headspace. the displacement over time is horizontal, not vertical as I understand this is slower takeoff and landing. had many close calls in the past with my other drone as the warning beeps and the battery was on its limit and it's still in the air 10 meters or so.