Split up your play time and you will have both more success and also enjoy it more. Hoping to get a win by continuing to play for more time then its enjoyable is probably one of the most common tricks a gambler will play on themselves to no great advantage. Play the same hours but later or another day will work out better all round.
Your piece of advice looks good, but remember that we're talking about slots. In other games more based on skills or that simply require your attention, having some rest when you're tired of playing is fundamental, but in slots all you have to do is push the spin button.
What I mean is that, tired or not, the results will be the same. A different thing is that, if you're tired, you can feel tempted to play more out of pure boredom, and end up spending more than the planned budget. In that case, I agree with you that having some rest can be beneficial.