I guess it depends on battery strength and whether it's a clear line of sight.
BTW.... you can also use your mobile device to control the cable box.
I even set my recordings from work when I forget something.
I have all four of my digital boxes in cabinets or closets. For almost a year I've struggled to get IR repeaters to work with Optik TV remotes. It's been very frustrating and Telus techs are completely clueless when it comes to IR repeaters. The entire concept is unsupported. The best results I had were with Xantech and Microsmith IR repeaters but they still didn't work like they should. The basic problem is, the Optik TV remote controls are junk. Absolute crap! You'll never get them to work properly with IR repeaters. Once I discovered that AT&T U-Verse remote controls work with Optik TV, my problems were solved and all of my IR repeaters now work perfectly. Shame on Telus for supplying such cheap remote controls. I bought four of the AT&T remote controls on eBay for about $8 each, brand new. The correct model number is: S30-S1A.
I used Xantech product.
I use a DL85K receiver http://www.xantech.com/Infrared/Infrared/LCDCFLProofIRRcv/DL85/
A 78944 connector block http://www.xantech.com/Infrared/Infrared/ConnectingBlocks/78944/
I don't recall the model of the emitters, but I think they are generic like these:
Here's what my system looks like:
Bought mine from smarthome.com a few years ago. Here's the Xantech catalog http://www.xantech.com/downloads/Xantech_Catalog_2015.pdf
Note: Placement of the emitter on the front of the PVR is critical.