SinBin
BA have tweaked the ruleset somewhat, but only if you bid low on credited hours on a month. I strategically block all my work up at the beginning of the month so as to avoid a forced assigned trip at the end of the month
Maybe you've been lucky or maybe that's a consequence of Short Haul roster construction.
Those DEPs considering/heading for Long Haul need to be aware that there certainly pilots, most especially the 744, who have been force assigned extra trip(s) having been at or very close to CAP. The "tweak" is more than a "somewhat" and bidding high /blocking the work at the front of the month certainly offers no protection from "Force Assign" (on any fleet).