An example which I observed myself not too long ago was someone who hadn't flown at all for well over a year. He was prescribed 8 hours in the sim (one session of training, another one OPC) and 20 sectors of line training. And it got him back to speed without any issues. In the ACMI and charter segment, you can routinely see people with interruptions of 6-9 months over the winter, it doesn't surprise anyone. In that situation, it's usually 8 hours in the sim and 10 legs with a trainer before being released to the line. Obviously, any of those numbers is subject to review and extension if anything in the individual's performance suggests a need for more training.
It's sure as day that you will be rusty after more than 2-3 months out of flying. Hence the 90-day rule. But it's not the end of the world and you won't have to learn the ropes from zero, as some may fear. Don't underestimate the importance of self-study while not flying. Review your manuals, maybe print out a cockpit poster and do some "armchair flying" every now and again. When the time comes, you'll be back to speed in less than a month.