Yes, but there are other ways of providing separation. Even with Procedural Separation, if one random track a/c is above (or below) the other a/c on the tracks that it crosses, then it is quite safe to allow it to fly on that random track. What tends to screw this type of operation up is the sheer amount of traffic at all the usable Flight Levels; so that attractive Flight Levels are simply not available for the Random Track a/c to use. This will be compounded by the Random Tracker cutting across more than one track during its journey.
In these circumstances, ATC will be particularly mindful of the density of one directional traffic (eg. the Westbound Flow) & will not sanction a "one off" Random Tracker. But, if they have vertical separation (& it can be maintained without adversely affecting the a/c complying with the Organised Tracks), then why not allow allow random tracking - on a very limited basis !