@DonTomGot the only “issue” you could have with your preload plan is that even if you plan your 2,45km @5:19/km segment like in your exemple, on the field there is a lot of chances that your segment will not be 2,45km (more or less, depending on terrain, route that could change, wrong direction… or so…) ; so I guess it would impact the rest of plan.
That’s why I set waypoints (on route, in Sunnto App) and use manuals lap during races to have current pace on lap and distance remaining to nextwaypoint.