It's good practice!
One of the highlights of all D&D games I've ever played was
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Finally levelling to the point I could cast 7th level spells, while the party was trapped on some awful demiplane where strange creatures were coming out of cracks in reality and just beating us to shreds.
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Learning Mordenkanen's Magnificent Mansion.
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Casting it so the party had some where to go rest and escape.
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Taking the party on a tour of the mansion and getting super prissy about it. "Here's the kitchen. Here's the living room, no feet on the couch! The guest rooms all have private bathrooms, everybody better wash up, and send your dirty clothes to be laundered before you touch ANY furniture!"
That game continued to epic level and that character (who I had played starting from first level over the course of YEARS) created this spell using the 3.5 Epic Spell development rules. It is the best spell ever.
