Truck AC service question

I have used those cans and a low side gauge 100 times and it has never caused a single issue. If I find a leak in the system and have to replace a part then I have the tools to draw it down and I use a gauge set. I replaced the condenser in my wife's van a couple of weeks ago. It had a really bad leak. The van has front and rear air and take 40 ounces from empty. I drew it down and then added 40 ounces using those small cans. It works great. Working on an R134 system is super easy if you have the basic tools. As to the low side only gauges.. I think I have like 4 of them. The Ollies near me sells a low side gauge for like ten bucks. Get your R134 and it's an easy fix. If you have a leak you will be needing to fix that though. With that said, years ago we had an old Volvo V70 that had a leak in the evaporator core in the dash. That old car was a junker that I was trying to push as far as it would go. So, I bought the recharge with the good stop leak in it, not the cheap stuff. It worked for the two more years that we had it and was working great when we sold it. Keep in mind that a low system will cause a lot of cycling of the compressor clutch and will wear it out. Then a leak creates all kinds of unanticipated stressors on other parts. In some vehicles it will cause a chatter when the clutch is engaging that puts stress on the belt and tensioner (see some years of GM/GMC SUVs and trucks). So, keep the pressures right or don't turn it on till it's where it needs to be.