Main problem is that forest has defense rate 1.3 and on same moment lowers the offense rate to 0.7. As a bonus, watchtower also adds extra defense. So when raiding a watchtower, guarded by 5+ members will be suicidal, unless you raid with a lot of members and are prepared to wait till end of war, where you win on skulls.
Most watchtowers will be build on forests, so logically there is some stalemate when a lot of defensive players can jump in pretty fast. For the offender there is not a lot of honor to gain there, unless he wants to have a special tile. But nowadays, better build a tower nearby and upgrade it to a higher level than the owner to claim it.
Unless they can avoid supreme victory and let their members be in such a war for 23:30 and win on skulls, it’s not smart to declare a war, needing a lot of your team. Say half of your team goes into such a war, the rest then needs to defend the watchtowers they already build. So that’s why strong teams definitely don’t go declare wars against equally strong teams for sure after a few days of conquest.
The setup of conquest isn’t perfect. We only score points by building new watchtowers, not for beating other teams. Having said that, we also see wars declared on resources, just to make sure the two other teams can’t take them. So two alliances deliberately declare wars on those and let the team who owns them win. Easy way of protection.