Scaling neural networks
I don't think you ought to change much in the model definition.

You should, however, consider the amount of time it takes to train on the complete dataset. If it takes too long and you are still in the testing phase, you want to reduce the number of epochs to obtain results faster and make changes in the model accordingly.

I suggest plotting all the metrics and try to understand if the trend is positive or negative. If it's positive the changes you are doing are correct of course!

Then, once you are happy with the hyperparameters, put like epochs=100 and leave the model to train for a whole night, then plot again the learning curves and decide when to stop earlier, or use early_stopping.