LaTeX can, by default, only cope with 18 outstanding floats;
any more, and you get the error "too many unprocessed floats".
This package releases the limit; TeX itself imposes limits
(which are independent of the help offered by e-TeX). However,
if your floats can't be placed anywhere, extending the number
of floats merely delays the arrival of the inevitable error
message.

Homepage:
https://ctan.org/pkg/morefloats
