If you are using shush/pat have a look at the link above but the section on naps option 1 which describes how to see your LO right through transition from one sleep cycle to the next, its a different W2S method, you help rather than disturb.
Between 3.5 and 5.5 months old I did not have luck with W2S either for extending naps (we had the short naps common with the 4 month regression) nor with early waking (he just woke earlier the next night) however at other times I had huge success with it and it was a real life saver when mine dropped to one nap at around 11 months. His one long nap went stupidly short (due to OT he woke every 20 mins) but I discovered I could do a super quick W2S, I was only in the room 2 mins to see him through that disturbance and by doing this he got a marvellous 2 hr nap and woke fully refreshed rather than screaming his head off.
I've seen many many threads where W2S has worked a treat for helping LOs this age - certainly worth a try.
Welcome to BW forums by the way - lovely to have you here