RXJava2. Do I need dispose streams which emits once? (Single, Maybe)

I have a lot of Single's in my code, such as

Disposable disp = Single.fromCallable(()-> loadData())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribeOn(Schedulers.io())
            .subscribe(res-> showInUI(res),
                    throwable -> Log.e(TAG, throwable.getMessage()))
            );

As I understood from the documentation, the difference between Observable and Single is that Single can respond with an error, Never respond, Respond with a success and it emits only once. Now I do not dispose anywhere and everything works fine.

So do I need to execute disp.dispose() at all?