This is not an entirely straight forward situation to answer. In other words, it all depends.
In the last year, I have been building my portfolio as the bull market has unfolded. While it might be argued that I would have made more profits by moving in much faster, there is a large element of hindsight in that suggestion. Bull and bear market trends unfold slowly month by month. In the early stages of a bull market the risk is higher than once we have seen a few peaks and troughs and there is more certainty that it is a bull move and not just a bear market rally. So, I will increase my holdings progressively as the evidence mounts that the trend has changed and the risk is therefore gradually reduced.
In this building phase, I will give a non-performing stock plenty of room while it stays above its stop-loss level. It is always the case that all stocks do not move up together. Some companies will go very quiet for months and then spurt upward in a short period. Transaction costs and tax considerations have to be considered and in general I give them time to work out.
However, when the portfolio process is finished and I am fully invested, my attitude has to change a little bit. Not a lot, but a bit. If I see a good stock that is moving up well, the only way I can buy it is to sell something I hold. The question is what to sell? I sell the ones that have not yet performed.
It is important to understand what I mean by not yet performed. I mean a stock that I bought and has never gone much higher. I would sell this stock before I sold one that had gone up quite a lot, but was now not going far very fast. There is plenty of room for argument about this one way or the other and I don't think I am any more right than someone who makes a different judgement. My view is based on the idea of letting your profits run. So I sell the ones with little or no profit, rather than the ones where I already have a profit to let run.