Video 1:  6 t-shirts were printed at one time.  From the video, you can see it is real time printing that 6 pcs of t-shirts printing only need less than 3 mintues.
Video 2:  6 t-shirts were printed at one time as well,  real time printing that 6 pcs of t-shirts printing need about 10 mintues.
Video 1 printing and video 2 printing, they are use same resolution for same size of t-shirts printing. What the differences are the model of print head, the quantity of print head used for one set of printer machine and the board.

DTG printer machine is different from DTF printer.  DTF printer is a printer supporting to print picture onto film, but not cloth while DTG printer can do.
The inkjet DTG (Direct To Garment) t-shirt printing machine uses a high-resolution print head to apply ink directly onto the garment, creating vibrant, long-lasting prints. It is a specialized printer that uses inkjet technology to print designs directly onto garments. It is a popular choice for printing custom t-shirts, as it is fast, efficient, and cost-effective.

DTG t-shirt printing machine means printing directly onto t-shirts.  We have A3+, A2+ and A1+ model textile t-shirt printing mahines.
For A1+ 6590 printer, it support to print at one time
1). 2 pcs of A2 size  ( A2 size is much bigger,  printer support printing, but if need it, let seller know )
2). 4 pcs of A3 size
3). 6 pcs of A4 size
It is one set printer for printing different with different qtys. The trays are adjustable.
Video 1 and video 2 show 6 pcs of t-shirts printed at one time

A1 DTG t-shirt printer
how to place trays for 6 tshirts

How to place the trays for 6 pcs of t-shirts printing at one time. Like the picture above shows:
Step 1:  the corner of the printer’s black glass flatbed table is the starting position.
Step 2:  make the X-axis of the tray marked 1 parallel to the X-axis of the platform, make the Y-axis of the tray marked 1 parallel to the Y-axis of the platform
Step 3:  let tray marked 2 touched to tray marked 1, and let tray marked 3 touched to tray marked 2, same to do it till tray marked 6 placed well.

Full t-shirt printing process, please check: