I am a firm believer in tearing down and cleaning my guns after each range session. For my range guns it may be a while before I take that gun out again and I dont want to forget its dirty. The reasoning for my carry guns always being clean is that my life may depend on the reliable operation of the firearm and I dont want anything that I can help to interfere with that reliability. hat being said there have been a few occasins when I took 3 or 4 guns out and maybe only shot one of them 30 or 40 rounds. If I know I will be shooting within a week I will plan on taking the gun that wasnt shot much and shoot it enough to make it worth cleaning. If you have shot 100 rounds and dont get around to cleaning it, the gun wont be harmed and should perform just fine for 100's of more rounds but if its used for your protection why risk a malfunction? At the very least I would run a patch or 2 down the barrel and wipe down the feed ramp area through the ejection port after each use.
Welcome to the forum and you've got a great gun in the Shield. Mine is close to 4 years old now and has been 100% reliable. I just had it out on Sunday for run and with 147gr ammunition it puts the holes right where I point it.