Shrinking T-Log file every weekend basis
I would recommend properly sizing the log file and not shrink it on a regular basis.

Because you are rebuilding the index you will grow your logfile as the index will be written to the transactionlog file. This means that your largest index should fit inside the transaction log file.

If your database is in full recovery mode, you can try to take logbackups more frequently to prevent it from growing out of hand.(Multiple index rebuilds stored in the transactionlog file)

If your database is in simple mode, this will not be the case.

When your transaction log file grows you will create something called Virtual Log Files (a structure inside the transaction log file) this can cause several problems. (more information: https://blogs.msdn.microsoft.com/saponsqlserver/2012/02/22/too-many-virtual-log-files-vlfs-can-cause-slow-database-recovery/)

I would first shrink your file, and then grow it to a proper size to avoid the creation of too many VLF's. But do not shrink them on a weekly basis.