I lean the Archer above 3500'. It has an exhaust temperature gauge which makes the process easy.
I tend not to lean the 152. I guess that is because:
1. I fly shorter trips.
2. I fly more locally, which means lower altitude (South East airspace).
3. There is no ET gauge, so rely on engine note to lean correctly. No biggy, but that gauge in the Archer is fun to watch.
Both aircraft are hired wet.
TG