We have seen for some time now junits timeout frequently on jenkins. This is probably down to it being a very loaded env. On circle we don't observe that behavior probably bc it's not so loaded.
The question is whether it is time to raise timeouts as they might be hiding legit failures. As en experiment I raised timeouts in a branch and ran jenkins against it. What I see is that the last 4.1 run had 14 failures out of which 12 were timeouts. Increasing timeouts reveals what looks to be 9 legit failures where 2 are timeouts that probably need to be investigated.