It last long enough for the purpose it serves. Despite what everyone wants it to be, it's not a lock on. I seem to be one of the rare few, if any that looked at the skill description and immediately understood what it does and how it works and was excited for it and made it my first r10 perk. When I saw people complain about it and videos of it, I was confused, it functioned exactly how I assumed it would and made me even more eager to get it, but people hated it, until I realized people somehow misunderstood what the skill is. Could it be a lower rank, sure. but I'd be greatly disappointed if it got removed.
Yes, for weapons with travel time, you need to aim ahead of the target, at the lead indicator, the R10 skill does exactly that, it's snaps, not locks, the aim to the indicator, it's literally a form of Aim Assist or what ever it's called in FPS/TPS games that you can snap your aim on a target if it's close to your reticle, it's usually optional though since it aims at the body. also, The skill does work on the hitscan RJ weapons, at least the pulsars, haven't tried the laser ones, the aim actually snaps to the enemy ship directly, still, not a lock on.
Actually, the only annoying issue I've had with the R10 perk is that the lead shots completely miss occasionally when they should hit, but I don't have to deal with that anymore since I've been using tether.