DHCP leases

Hi all,

So, I have about 20 PC’s on my Network, but other devices connect to my router like Laptops, Mobile Devices and so on, the DHCP started releasing IP’s with 192.168.0.196…192.168.0.195, 192.168.0.194…then ...180, ...123…...47, ...45, ...44…...25… ...18, ...13, ...9, ...3
I want to understand how the DHCp works, because some PC’s have static IP and I don’t want conflicts on my network, why the DCP didn’t assigned IP’s one by one, but with such big gaps between them ?

Thank you.