Learn Turkish: Mesai bazen saat altı buçukta bitiyor. - Sometimes the shift finishes at half past six.

This ties into our lesson about Saat kaç? (What time is it?) vs Saat kaçta? (At what time?). Because we are saying the shift finishes at half past six, we must add the locative suffix -ta (meaning "at") to buçuk. If we were just stating the current time as "It is half past six", we would only say Saat altı buçuk.

Why is the "at" suffix on buçuk spelled -ta rather than -da?

This happens because of consonant mutation. Since buçuk ends in a hard consonant (the letter k), the "at/in/on" suffix -da must change its "d" to a hard "t" so it is easier to say, becoming -ta.

Does the word saat always come before the number?

Yes! When stating a time in Turkish, saat (hour/clock) comes right before the number. To say "six o'clock", you say saat altı (literally "hour six").

Why use the continuous -iyor tense for a routine like "Sometimes the shift finishes..."?

In Turkish, the present continuous suffix -iyor is used for ongoing actions ("is finishing" right now), but it is also very commonly used for general habits and routines. It sounds completely natural here to describe something that happens bazen (sometimes).