My wall was 410,000 point, it was burned down weeks ago and till now it's still burning, as my calculation the my wall recover rate is about 900 points/hour (in another case I calculated 700 points/hour) - my calculation may not be correct but just assume that is the fact for this suggestion, it means it will take 20+ days to recover, nearly 3 weeks, but this strategy game is somehow very fast, 3 weeks to recover a wall is too long to keep playing.
Firstly, I suggest wall will be recovered in 2 weeks maximum. Wall will be fixed in 1 - 14 days no matter how large it is, recover point per hour = total point / (14 x 24).
Another issue is I set 134 level 8 units to protect my wall, like 8 gold/10 silver units, attackers are level 9 - 10 units, it's surprised me when it takes about 30 minutes to burn down 410,000 points and they don't die any, only a few. It's not 'art or conquest' to me when wall is soft like noodle and army is weak like paper.
I suggest each level of wall will add 5% attack speed and power to archers on wall and 3% attack speed and power to army under the wall (may limit to 100% maximum). Let imagine when you fight under a great great wall compare to enemy with nothing at his back, what do you feel ? stronger, more agile, more power, of course.
Also, wall will have some barriers (level 20+), moat (25+), pit (30+).