Angel Island features a system called Gain Waits. Simply put, once you gain a skill, (above 80 points) it is impossible to gain another for a set period of time.
There are no gain waits below 80 skill.
Gain Waits are as follows:
80-90: 36 seconds
90-95: 72 Seconds
95-99: 90 seconds
99-100: 6 minutes
Additionally, stats (Str, Int, Dex) can only be increase every 3 minutes. As with skills, once you gain in a stat, it is impossible to gain any stat for 3 minutes.
What this means for you
By building gain waits into your macros, you will save resources and train some skills faster. For example, if you are training Magery and you are at 92, you would cast Flamestrike/Water Elemental repeatedly until you received a gain. You would then pause for 72 seconds before repeatedly casting again. As you can imagine, this saves you a great deal of reagents.