Using Queen and Chrono Boost Effectively

As JavadocMD pointed we have discussed Queen usage at length. To help extrapolate on the Queen consider the following: If you have 3 or more Hatcheries, its likely that you're approaching the Control cap. At this point is it really worth it to produce additional Queens which will not be involved in battle? The Queen does work as an efficient defensive unit, but Spine/Spore Crawlers can also function in this roll and require no additional Supply. Additionally, if you have more than 3 Hatcheries, your production is very high, and as those bases become mined out, your income will not be as high. Thus its often less worthwhile to produce Queens at bases after your first expansion or two.

On the subject of Chrono Boost, I often find it hard to spend efficiently late game but here are a couple things that may help:

• Warpgates can be Chrono Boosted
• Research can be Chrono Boosted
• If you have as many Robo/Starport as Nexus, you can often Chrono Boost them
• If you have more than 50 energy on a Nexus you can spend it on two buildings (instead of having to wait for it to finish off on one).
• After early game, Probe production slows because its usually constrained by the number of expansions you are bootstrapping

For what its worth, I still have the habit of cycling through my Hatcheries every ~25 seconds to guarantee effective usage. Because of smart cast I can even leave all my queens in one group if necessary.