I had a colleague who told me his secret - "I just say 3 or 5 to anything". That was it. He would pause, then say 3 or 5. Anything I was asked to estimate, I'd give real effort estimates based on their scale. And was always pushed back on like you noted above. And it was a constant struggle. Yet... I always (like... over 95% of the time) hit all my targets, delivered early, and would sometimes pick up the other slack. The other guy with 3/5 - would almost always get pulled in to some other project (or aspect of the project) so almost never got his stuff 'done' (often I would finish it). But on paper... his estimates were always 'so easy' and his tickets always got done (often by me) but I was the 'difficult' one (for many other reasons beyond this).