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Is it 'against the rules' to use several columns exceeding 12 if they are hidden with visibility classes?

For example, would there be any issues (technical or standards wise) using the below:

<div class="row">

<div class="medium-6 column">
</div>

<div class="small-6 column show-for-small-only">
</div>

<div class="medium-6 column show-for-medium">
</div>

</div>

gridcsscolumnsRows

For example, would there be any issues (technical or standards wise) using the below:

<div class="row">

<div class="medium-6 column">
</div>

<div class="small-6 column show-for-small-only">
</div>

<div class="medium-6 column show-for-medium">
</div>

</div>