As it stands, it's near impossible to get crests to level 25 without using Max Enhancers, which are incredibly rare from my experience. Most people are locked into a constant cycle of raising some crests while lowering others and never get any higher than 20.

What I propose is a new crest enhancing system. While it will make it so enhancers are no longer random, it'll create a more enjoyable experience. I for one just used 68 enhancers on a single crest today, only to have it drop from 17 to 13. Needless to say I was beyond frustrated.

The new system would let you select a crest and it would give you a percent chance of success when trying to enhance it. Using more enhancers at once will raise the chance, making upgrades more reliable. Of course Max Enhancers would still be relevant, as the higher levels would likely take a lot of enhancers normally. (On a side note, rename Max Enhancers, they're very misleading. The name implies that it raises a crest to max level in one use, not that it has a max chance of success to raise it one level)

Personally I think its fine the way it is. You can get max enhancers from call to arms event for castle 19+. 68 enhancers is really not much. I usually spend 300-400 enhancers to get a single crest to 20 or 21. My worst luck is about 800 lol.

Be patient. It takes time to max out your heroes but its rewarding when you get there. I would advice you to use 2 or 3 crest on your heroes(depending on your hero) for now so that your heroes can still put a decent fight in battles.

I have 10 heroes all max crests levels atm. 3 of them arent level 80 yet but its getting close. Keep in mind that I dont know the right way to max crests level before so I have to spend way more max enchancers to max my heroes out because I have 4 crests on them..

That explains it, K5 doesn't have many people at or above c19. This is part of the reason why I'm starting on a guide for the game, there's so much that's not apparent or poorly explained about the game, unless you get to a higher level which takes quite some time to do.

How many points do you need to get Max Enhancers by the way? I can't imagine them being at the lowest point thresholds.

I agree that there arent much guide for the game. You will learn the game slowly though by playing and looking at the reports and stuffs. 

As for the max enhancers, there are multiple ways to get them from c19+ call to arms event.

1. Reach certain amount of points in CTA. 1 at 120k and another at 240k. Seems alot but dont worry because this wont be where you get most of your max enhances!

2. Rank top 50 in the event. At 80k points you will be ranked and are guaranteed to get at least 1 max enhance. 2 for top 10, 3 for top 3 and 5 for rank 1.

3. Dragon treasures. There are dragon treasure III and IV with the latter being better but harder to get. You can get dragon treasure III quite easily daily as you only need 4k or 10k points.

You can get crest to level 25 using All Enhancer.
Yes, without using Max Enhancer.
Try piling up more All Enhancer and use them one shot. Still, it depends on luck.