“At home” or “home”

Aturan penggunaan At pada home? Sebagai contoh. When he called me I was (at) home. I am always (at) home on Sundays. He came to my place at 6pm and by that time I had already been (at) home. Hello! Is anyone (at) home? I am (at) home at last! I am always complimented (at) home.

Aturan  At 

1. At menjadi opsional ketika kata Home sebagai pelengkap bentuk Be ( am, are, is /was,were,been)

    I was at home.

2. At wajib digunakan ketika Home menjadi modifier (pengubah) 

    I am always complimented at home.

3. At tidak digunakan setelah kata Go, Come.

Tapi saya yakin masih ada beberapa pengecuailian pada aturan ini. Seperti contoh, pada soal

 - He came to my place at 6pm and by that time I had already been (at) home.

Dimana At mengubah arti pada kalimat. had already been home menjadi arti idomatik pada kata Been yang sebagai bentuk kata kerja ( verb of motion) dan kalimat itu dapat berarti I had been home and gone away again.