Split your Laravel daily logs by year/month folders

logging.php

<?php

// ./config/logging.php

return [

    /*
    |--------------------------------------------------------------------------
    | Split your daily logs by year/month folders
    |--------------------------------------------------------------------------
    |
    |    ./storage/logs/
    |
    |    ├── 2018
    |    │   └── 12
    |    │       ├── laravel-2018-12-30.log
    |    │       └── laravel-2018-12-31.log
    |    └── 2019
    |        ├── 01
    |        │   ├── laravel-2019-01-01.log
    |        │   ├── laravel-2019-01-02.log
    |
    |        .....
    |
    |        │   ├── laravel-2019-01-30.log
    |        │   └── laravel-2019-01-31.log
    |        └── 02
    |            ├── laravel-2019-02-01.log
    |            └── laravel-2019-02-02.log
    |
    |
    */

    'default' => env('LOG_CHANNEL', 'stack'),

    'channels' => [
        'stack' => [
            'driver' => 'stack',
            'channels' => ['daily'], // set 'daily' channel
        ],
        'daily' => [
            'driver' => 'daily',
            'path' => storage_path('logs/' . date('Y/m/') . 'laravel.log'), // add dynamic folder structure
            'level' => 'debug',
            'days' => 31, // set the maximum number of days in a month
        ],
    ],
];

This won't work if you cache config files.
I have another custom implementation here
https://gist.github.com/arun07as/30a3983cf03d0e40afac450a842ad4f7
That extends monologs RotatingFileHandler to generate custom file paths