First, I'm sorry to hear your struggling with this.....but I also wouldn't call this happening 5X a year as just "occasional."
My surgeon and I have had this conversation several times--even just yesterday morning at a post-op visit!!!

Anytime there is catching/locking, it's almost always from a loose "object" in the joint, creating a mechanical problem. Mechanical problems are bad and lead to damage to other joint surfaces in your knee. The clicking doesn't seem as concerning as the locking. I've had locking/catching 4-5X in the last 10 yrs--Sometimes while simply walking, but at least 2 were going up/down stairs. I had it happen this last Feb. and April actually. Every time, this has always resulted in surgery, and it's usually the final straw while toughing out or trying to see if PT would help avoid another surgery (I've now had 10 in 19 yrs).
Don't laugh---but I actually had Microfracture surgery (with Biocartilage fill) 5 wks ago. It really sucks to get stuck on your stairs from the knee locking----while your husband is out of town----AND when you have a young son to take care of.

I worry one of these days, you're going to have this happen when you're NOT at home.

Especially with the increase in noise/clicking.
If you start having issues with your quadricpes, just above the knee, you'll know it's time for surgery. It was a new symptom for methis time (very odd, after 9 other knee surgeries!!). The muscles just were not firing correctly. The area nearly "shut down" (for lack of a better phrase) while I waited on the surgery date set for 3 wks out. By the day of surgery, my quad muscles were painful to the touch and not "firing" correctly at all. My knee would hyper-extend for no reason, and stairs were impossible. I'm a die-hard "never miss a workout" person, but I had to completely stop everything except walking those last 3 weeks. Now I know this new symptom was due to a very large piece of articular cartilage broken off from my tibial plateau articular cartilage. I basically had a "pothole" on my lateral tibial condyle, and part of the pothole "stuff" had come out and was banging around in my knee.
Fast forward---At my post-op visit, the surgeon said the loose body stuck in the joint was what surgeons describe as HUGE.

That's why I was having such muscle shut-down----these types of mechanical problems lead directly to the muscles not firing correctly. Plus, it had banged around in there like a pinball, causing more articular cartilage damage and inflammation than I already knew existed from an MRI last Summer. There were so many floaties, he had to clean everything out before finding the main problems and figuring out what to do first (ha)!!
Then he proceeded to remind me if I want to keep putting off knee replacements on BOTH knees, we must go after the loose pieces as soon as I suspect or get those same feelings of locking/catching/etc....I should be pretty good at it after 10 knee surgeries and 20 yrs.
I get tired of the 2-3 yr surgery cycle, but I also want to keep my own parts for a few more years. He's done my last 6 procedures, and he's on the cutting edge of articular cartilage repair, so at least I'm blessed with a wonderful surgeon.
My final piece of advice---the longer a loose piece floats around in there, the more damage is being done to your OTHER joint surfaces. I've been the trooper who refused more surgery and said I'd wait and deal with it. That almost got my right knee replaced in 2015. Luckily, I go to this great surgeon I mentioned who performed a successful ACI procedure on that knee and bought me a few more years..but I don't EVER want to go through ACI again!!!!

--Lisa