I am a road racer too. But can really recommend doing some cross country races when you prepare for a spring marathon. Good workout and helps strengthen your body.
But we are a slight bit off topic now

.
Some questions about track recognition mode: what does the "lap alert" feature mean in practice? Is it additional to the laps I programmed in a structured workout, meaning it alerts every 400m? And where is the lap start/finish?
I programmed a 10x400m workout for this week and I want to do it on a "real" track. My warmup is open and my idea is to start the workout exactly at the lap track marker. So when running on lane 1, I should exactly hit the marker every round, correct?
I thought I knew what lap alerts were but as I looked deeper into it, I think I don’t have the full picture. What Watch records both Laps and Intervals. Intervals are the distances recorded per your workout. Laps I believe is 400m or less if your recovery or workout is less?
But I think I can answer your other question about how to mark where to start. You don’t have to start exactly at the official track marker (e.g., sometimes depending on how the wind is blowing I may want to start somewhere else). Wherever you start will be the place where the marker will be counted for the distances you cover during your workout and recovery/jogs.
It also means you don’t have to be precise where you start, although as a habit I try to be because Rather than relying on the watch to tell me when I have completed a distance I just rely on the marker. My former track coach used to tell us to RUN THROUGH the marker because so many are prone to starting to slow down as we arrive at the marker. Just run through it like the marker was far ahead of the official marker because you don’t want to slow down ahead of the marker!
Here‘s a small example (truncated) of what the workout records for the following workout:
3 x 1200m, 3 minute recovery between intervals; then 3 x 200m, 1 minute recovery between intervals
I have a suggestion for your first time using the track detection feature. Create a fake and short workout just to test all the functions you want to get a sense of how to use the feature.
You could do, for example:
2x 250m, 150m recovery jog between intervals
1x 400m, 200m recovery jog
See what it records and see what you need or don’t need to press.
For me, my warm-ups are always Open (no time and no distance limit). When I’m ready, I get to the marker, then I press the Action button to indicate my workout has started and then I basically don’t need to touch any more buttons for the entire workout / recovery session. My last part is the Cooldown which I also include but is Open (no time and no distance limit) so to end the workout I either press two buttons to pause the workout and then press End.
Hope this makes sense.