Most areas have more than one enemy, even some boss areas are comprised of several enemies and the boss.
It's not overwhelming numbers, then again, when even the most simple enemy in the game, the Drebling, can kill you easily, fighting more than two of them at the same time can be hellish ;)
Oh, and prepare for large numbers on the first Boss fight. Phalanx divides himself into more than 20 small versions, each one can throw a Spear that can easily cut 3/4 of your health, even with Cling Ring.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"