Toptobottom;
Sometimes we have to hover in the middle of a heliroute, and often do.
If a twin is hovering 'on task' in the middle of a heliroute then ATC will often close that heliroute to other traffic unless we can accept visual separation.
In a recent conversation I had with LAATC;
If the 'operating' traffic is within 1 mile of the heliroute that the 'transit' traffic is following then visual separation and thus passing is usually permitted. If it's beyond 1 mile from the heliroute then SVFR rules apply and 3 mile/1000ft spacing required so the route is made unavailable for transit.
But this doesn't mean you can wonder off the heliroutes by up to 1 mile and still be ok.
regards, MB