My two run around (in open fields, so no risk of getting tangled in bushes etc) just as mad with haltis on as off. So you could leave it on if you wanted. It's actually a good way for them to get to like it more, as the then don't associate it with being on a lead all the time.
if you want to get him to not think 'halti means end of walk' I'd keep swapping.. let him run around for 5 mins with it on, call, reward, take it off... 5 mins later call, reward, put it back on... let him run around some more and so on! Particually good if 'halti on' means something fun, like having a ball thrown, 'halti off' means ball goes away and you let him go sniff around