Question about skills above 99

Now, if I've understood it correctly, some skills don't benefit from boosts above 99, for example mining. This means the dragon pickaxe special and celestial ring are useless when you reach 99 mining. Is this true for all skills? If not, is there a list of which skills benefit about 99 and which don't?

Is saturated heart useless when your 99? Is prayer gear useless when you hit 99?