How can I hang lots of pictures without drilling too many holes.

Command hooks.

Picture hangers do not need drilling for installation and need only one or two small holes created by driving a thin nail into the plaster. I'm assuming plaster since you did not specify wall material.

There are a lot of different command adhesive mountings to consider.

However having relocated a lot and having a huge art collection -I find that picture hook nails are incredibly easy to fill with spackle and repaint- as I would do this before listing my home for sale. You may wish to reconsider.

I have used a hammer and picture hanging hook— not a drill.

If you wish not to make a small hole with small nail and hammer consider looking at this link

https://www.command.com/3M/en_US/command/products/~/Command-Products/Picture-Hanging/?N=5924736+8706801+3294529207+3294857497&rt=r3

Command has Velcro strips now for hanging pictures. Hold well and come off easy when needed. Bonus, no holes in walls ♥

Hang the first one very high on the wall with a sturdy nail/fastener.

Hang the rest from the bottom of that picture frame.

Repeat until you've completed hanging the rest your pictures.

Keep checking that the nail is holding under all the weight of so many pictures.

How about command hooks?