Don’t mix implicit and explicit waits. Part of the problem is that implicit waits are often (but may not always be!) implemented on the “remote” side of the WebDriver system. That means they’re “baked in” to IEDriverServer.exe, chromedriver.exe, the WebDriver Firefox extension that gets installed into the anonymous Firefox profile, and the Java remote WebDriver server (selenium-server-standalone.jar). Explicit waits are implemented exclusively in the “local” language bindings. Things get much more complicated when using RemoteWebDriver, because you could be using both the local and remote sides of the system multiple times.
This is how that would work: local code -> Java remote server -> local Java language bindings on the remote server -> “remote” component like the Firefox extension, chromedriver.exe or IEDriverServer.exe. It’s even more complex in the grid case, since there could be other hops in between.
Thus, when you try to mix implicit and explicit waits, you’ve strayed into “undefined behavior”. You might be able to figure out what the rules of that behavior are, but they’ll be subject to change as the implementation details of the drivers change. So don’t do it.
You shouldn’t be experiencing “hangs” when an element can’t be found if you’re not using implicit waits. The driver should throw a NoSuchElement exception immediately.