from logo help:
LOGO! restricts the nesting depth for your circuit program. Your circuit program has a maximum nesting depth of 58 objects.

This determines the following::

+
+

1 input
56 blocks
1 output

max. depth of the program path::

=

58 objects

During a simulation or download the system returns an error message if you enter a program path in LOGO!Soft Comfort that exceeds the maximum nesting depth

Implementing longer program paths

Longer program paths can be implemented by means of signal recursion. This is done by appending a flag block to the end of the path. The remaining blocks are connected to the output of the flag block. LOGO! interprets the flag as output of the first program path and also as terminal block of the downstream blocks. LOGO! interprets the long path with flag as two separate paths. If no more flags are available, you can use an output block instead.

i hope that helps you