I've not used the flexi-link as I've always used tenderlinks without any problems...
Even though it says a set can be left in for either 48 hours or 72 hours, some people find this isn't necessary so and they have to change a lot earlier, and you find this with all the different pump manufactureres and the particular sets, some people will find that they sets will do what it says on the box, others find it doesn't, some find it extremely difficult to get a type of set that works well for them...
If you find that you start raising at a consistantly before the recommended time i.e 46 hours on the 72 hours sets, then this is your duration time and you will need to be changing your set at the earlier time...
Give rouche a phone and ask for a sample of all their infusions sets to try, then perhaps you may find one that works better for you, also remember if you are getting occulsion etc as you can return the box's part full or full ones (for different batch numbers) replacing the duff ones..
I would also check out the other pump manufacturers that use the luer lock systems, phone them ask for a sample of their infusions sets as these might be more suited to you as an individual than the rouche ones. As sometimes it's the lubicants used during the manufacturing process that can cause individuals to have problems..