sampler2D and samplerCube in one shader - opengl

Question

I'm trying to use sampler2D and samplerCube in one shader. I used to do this using struct for several sampler2D. But now I decided to stop putting them in the struct and noticed several features. If I put sampler2D into a struct, it is sufficient to bind the samplerCube 1 time. But if I put sampler2D outside the structure, I will have to bind samplerCube each time I draw each model. Below I give examples of pseudocode.
sampler2D into struct:
uniform samplerCube shadowMaps;
uniform struct Mapping {
sampler2D ambientMapping;
sampler2D diffuseMapping;
sampler2D specularMapping;
sampler2D normalMapping;
} mapping;
C++ pseudocode:
// somewhere in init
// samplerCube
glUniform1i(shadow, 4);
glActiveTexture(GL_TEXTURE4);
glBindTexture(GL_TEXTURE_CUBE_MAP, shadowMapId);
// ...
// drawing models
for (size_t i = 0; i < MODELS_COUNT; i++) {
glUniform1i(model[i].ambientMapping, 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, model[i].texturesIds[0]);
glUniform1i(model[i].diffuseMapping, 1);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, model[i].texturesIds[1]);
// analogically for specular and normal
// model
}
sampler2D outside struct:
uniform samplerCube shadowMaps;
uniform sampler2D ambientMapping;
uniform sampler2D diffuseMapping;
uniform sampler2D specularMapping;
uniform sampler2D normalMapping;
C++ pseudocode:
// drawing models
for (size_t i = 0; i < MODELS_COUNT; i++) {
glUniform1i(model[i].ambientMapping, 0);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, model[i].texturesIds[0]);
glUniform1i(model[i].diffuseMapping, 1);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, model[i].texturesIds[1]);
// analogically for specular and normal
// samplerCube
glUniform1i(shadow, 4);
glActiveTexture(GL_TEXTURE4);
glBindTexture(GL_TEXTURE_CUBE_MAP, shadowMapId);
// model
}
Why in the second case I should everytime do glBindTexture(GL_TEXTURE_CUBE_MAP, shadowMapId)? And what is the best way to do it? What will be more productive?