I've used liners forever or longer. I have seven boxes in this house and all but one has a liner. The box with the liner doesn't get used any more than the others.
I've noticed that the cats claw up the sides more than the bottom, but overall I prefer the liners because it prevents the boxes from absorbing all the odors and I don't have to replace them.
When I change liners, but not all the litter,after I scoop I just put a new liner beside the box and set the old on in it. Then I put the whole thing in the box and dump the old liner by sliding it out, throwing it in the trash bag that goes to the burn barrel.
I always buy the Johnny Cat liners. They come in a 2 ml thickness where all the others seem to be much thinner at 1.5 ml and tear a good deal easier.
When I bought the Booda Clean Step, I bought the liners to go with that and promptly sold them on ebay after I found I could use the Johnny Cat with better results. I also use those Band-It Outdoor trash bag retainer bands to hold the liners in place to prevent them from just being pulled down into the litter an buried.
When I feel it's time to replace the box I don't use a liner in, I will use a liner in its' replacement. For me they serve a good purpose.