Some of the pinyin seems to follow the "written pronunciation" while others seem to follow "spoken pronunciation".
For example, 不客气 is displayed as bu2ke4qi5 - following spoken rules, e.g. the first of two consecutive fourth tones is spoken in second tone.
But 手表 is displayed as shou3biao3 - following the written rules. Because the spoken rule is that the first of two consecutive third tones is spoken in second tone (e.g. shou2biao3).
I think that they should all follow the second example- as that's how dictionaries, etc... tend to list them and it makes it easier to learn 不 is always bu4. Then you just need to learn 3 or 4 pronunciation rules.