If you overtighten you can strips the soft threads in the aluminum case. If you undertighten, they'll fall out and the transmission will leak. You can buy a torque wrench for under $50. If you want to work on modern vehicles with aluminum parts, using a torque wrench is s a MUST.

The problem comes from over tightening the little tens. If you have the proper feel for a little bolt versus a big one then you don't need to torque.

well the torque setting is very light like 7 ft-lbs. Experienced people know how much to tighten by feel and/or sense. You may get away with it bc you know not to crash the gasket.

always torque to the recommended torque and it's never very tight and tighten diagonally as recommended,

I am going to change the trans fluid and filter on a Toyota Camry 4 cylinder. I see some videos that show the pan being tightened down with a torque wrench. Is this necessary ? I have replaced a few of these in the past and never torqued them down, never had a problem with leaks or other. Any advice, suggestions, links, or videos about this ?