4.1 Improved phrasing

Author: Froussios

Part 4 - Concurrency/1. Scheduling and threading.md

@@ -162,7 +162,7 @@ This is very useful if you, as the consumer of an observable, know that processi
 
 ### unsubscribeOn
 
-As we have seen, some observables depend on resources which are leased on subscription and released when subscriptions end. Typically, releasing resources is cheap, but there can be cases where releasing a resource may require ceremony, e.g. coordinating over a network. If you need control over the thread that will execute the unsubscription code, you can define that with the `unsubscribeOn` method. 
+As we have seen, some observables depend on resources which are leased on subscription and released when subscriptions end. Typically, releasing resources is cheap. In exceptional cases, where you need the unsubscription actions to not block, you can specify the scheduler that will execute those actions with `unsubscribeOn`
 
 ```java
 Observable<Object> source = Observable.using(