I'd say the line's open most weekends (I sometimes travel to Ipswich for the weekend). Stuff wears out and weekends are the best time to do engineering work, so you'll always end up with a certain number of closures (on a 4-track line they can sometimes close one track pair at a time, but that line is 2-track north of Chelmsford). Some of it may be Crossrail-related work (I understand there are changes to Bow Junction planned). But I'm not conscious of it being worse than any other line.