Most of the ways really don't need a layer tag. The tag is normally used for bridges or tunnels, when two ways are crossing. The layer attribute says which one is on top.

Auch interessant:
osm.wiki/DE:Bicycle/Radverkehrsanlagen_kartieren

Danke für die Rückmeldung.
Ich denke, dass das englische wiki recht klar ist: osm.wiki/DE:Bicycle
highway=path passt eigentlich immer, man muss halt mehr explizit angeben.
Ob etwas passend dargestellt wird sollte nachrangig sein, insbesondere, wenn es nicht um die Darstellung auf
osm.org geht.
Wichtiger aus meiner Sicht ist es, dass
die Angaben wie z.B. bicyle=designated/yes/no passen.

Thanks for the feedback :-)
See also
http://gis.19327.n5.nabble.com/Is-JOSM-responsible-for-tags-like-layer-Main-Street-tp5860983.html

Thanks for the feedback. It happens quite often with JOSM, maybe it is an error in the
editor. I've noticed that once: Clicked on name
and JOSM showed the lanes field, clicked on lanes and JOSM showed the name field. Unfortunately I was not able to reproduce it after a restart of JOSM.

OK, thanks for the feedback.
I will remove the tags when I stumble over them again.

Hi there,
I've found a few roads with tags like
layer="Carrer del Llatzaret"
I've changed layer to name. OK?
changeset/35559727

Hallo!
Ich habe node/3855140400
auf traffic_calming=island geändert. OK?

Hi there!
I've noticed that a few objects where mapped with e.g. elevation=92
or layer=92
I've changed them to ele=*, see
changeset/35553021
OK?

Hi there!
Was was meant with layer=PAR?
way/246277309

Hi there!
Please help me to understand:
I found roads with layer=-1 or
layer=1;2;3 in this area. What do you try
to map with these values?
Is it meant to work as a 3D mapping?
way/237289952
way/237296886
way/232474265

Hi there,
IVe changed layer= "龙泉路" to name="龙泉路" . OK?
way/208011850

Hi there!
I fear something went wrong here:
layer=hedge on a bridge
I tried to correct it, but have no idea where the hedge is:
changeset/35551799

Hi there!
I've change layer=gr2 to track_type=grade2.
I hope that was meant ?
way/245232106

Hi there!
I've changed layer=Tranquil Lane
to name=Tranquil Lane
OK?
changeset/35551531

Hi there!
What was meant with lanes=90 ?
I guess the correct value would be 2?
way/372207185

Hi there!
I've noticed the unusual tag
surface="1.862 ha"
which seems to describe the size of the protected area.
I think there is no need to map the size
in OSM, but if you do, I think a tag like area_size="1.862 ha" is much better.
The attribute surface is for values like grass,gorund,asphalt.
OK?

Hi there!
I've notice two ways with
highway=гт
There is also a long way with
ford=yes close to it which is not
connected to a waterway.
See area around
way/381720699

Hi there!
I've just fixed the invalid tag
highway="residential; service"
on way
changeset/35547287
I guess it was not intended, do you remember what you did to create it?

OK, thanks for the feedback :-)