Yes, I'm doing these swims as 150m intervals rather than as continuous long blocks because I don't want my stroke to fall apart. The rest between is short, no more than 5 seconds, because I'm not aiming for speed right now. That can come in April, after the trip is over. Last year I started doing speed work in February and felt a bit burned out by July.
The cold water swimming article is interesting. I wonder if I could summon up a hot flash or two during my next chilly lake swim. :-)