Yeah, agreed. I don't usually have any issue doing Assassinations quickly, but as it stands it's still a really poor mechanic in a few different ways.
- When the only thing you need in a system is a new USS, waiting for one to spawn is time consuming and more importantly completely devoid of any real gameplay. It's even worse in sectors that are just a sun with empty space, if you happen to accidentally accept a mission awful enough to send you there. There should be a way to essentially 'ping' for USS signals, actively, so that you can start moving along to the next one without spending potentially minutes drifting through space with no activity.
- The idea that USS or other forms of random waiting are required for some missions is insane. There are a few ways to make that less terrible: Like was mentioned, adding a 100% guaranteed USS to a system if you've got an active mission that needs it, and/or adding some way to identify what a USS is going to be before dropping out of supercruise. For example, "combat readings" when it's some feds or bounty hunters and pirates, "high ship concentration" for trading convoys and wedding/funeral barges, and so on for mission-specific stuff like Black Boxes or Assassination Targets.
It's cool that they added a mechanic that's supposed to randomly give you something to do while flying between stations or whatever else, but it's hurt badly by the number of USS events that are completely useless and the number of missions that rely on finding a specific USS. There needs to be at least some major change to this system so that it isn't just wandering around empty space getting disappointed a lot.
Also, for assassination targets specifically, it would be nice if there were a better way to seek them out by other more "realistic" means. I'd love to see them flying around real space and able to be Interdicted, it would feel much more satisfyingly like hunting them down, and it also wouldn't hurt to have things like Pirate Lord targets spawning at nav or resource beacons or General targets spawning in warzones.