Labour ‘throwing the kitchen sink’ at Selby byelection as hopes grow of shock win
I can't see how that could really work out well. If Labour do get the seat, they will send a signal that they can win similar seats in the General Election when it occurs, but they will not be able to "throw the kitchen sink" at every such seat, so it will give a false impression of their ability to win. And of course, there is a very high chance of letting the Conservatives win by spittibg the vote.

Probably the best result is if Labour do throw the kitchen sink at the seat, but the LibDems still win. In that case, maybe more intelligent tactics will be used for the GE.