That's a pretty good question, I believe. One without clear historical hints.
I mean, both happened in the past.
"Sell in May and go away" is an actual saying coming from the stock market which has proven its reliability over time. And since the general trend in crypto and stocks was similar for a long time, the same approach made sense in crypto too.
The reasoning behind this pattern is that summertime is when most vacations and plans for vacations happen, and people are less focused on their investments or on buying more (might even sell something to fund their vacations). So, if the offer remains or grows, but the demand is not as high, prices slowly retrace.
At the same time, less volume over summertime is an opportunity for bulls to take on higher levels, even if it can be relatively short-lived (1-2 months), unless excitement is built up and a higher wave of buyers is engaged.
That is why we have seen some summer rallies in crypto in the past. Keep in mind that if prices go up significantly, some of the investors who took the other option of selling in May to go away until fall, would re-enter the market and amplify the uptrend.
So, where are we in crypto now? Hard to say. I mean, we've had a significant uptrend on BTC and some of the alts. Is that it? I'm inclined to say it isn't. I don't think this uptrend will end without BTC reaching another ATH, since it is so close to it and didn't drop below 100k. Plus, the price seems to jump like on a staircase pattern since the beginning of April, and we are now on the "3rd step" (a little below it, which is why the question whether this is time to "sell in May and go away" or not).
Will this uptrend culminate with an alt episode, like we have seen ETH and a few others pump recently? Possibly, but I believe its full power will be in the late fall or winter.
If the scenario that the uptrend will continue after a little break on this "step" proves to be true, I still think we will have a period of cooling off during mid-late summer till September, before the last big uptrend starts.
The alternative is that we will have a boring summer, slightly in the red, perhaps interrupted by very short volatility periods, but I don't see that happening if anyone wants Q3/Q4 to look like the end of a bull market. Maybe if they push it to Q1 next year.
What do you think will happen?