I have had two or three partial tears. One time I just had soem bruising and tenderness, but no swelling, so it may have been a tear or it may not. But twice, they were pretty damn clearly pec tears. I even heard the “pop” one time. Pec tears are a function of benching heavy weight raw full-range as well as technique and hand placement. Raw, I am strongest with a maximum legal grip. Unfortunately, that also predisposes me to pec tears.
The good news is that partial tears- typically in mid-belly, kind of near your armpit- heal up pretty fast. With my tears, I laid off benching for a week or two, then came back using a shirt for board presses for a couple weeks. Within a coupel weeks of the tear I started doign a lot of very light DB presses (10 or 15 lb bells) and evetually some flies. This is largely done by feel- if it hurts, stop what you’re doing. Within 30 days, I was back to normal.
I also used a baseball or even just my fingers to dig around in the muscle to try and bust up the scar tissue. Pec tears seem to leave a very noticable lump in the tissue. That lump will predispose you to more tears near the scar tissue. After a month or so, I was able to work the knot away.